Exhibit 8.1

Principal subsidiaries

The following is a list of Ternium’s subsidiaries at December 31, 2008.


			Percentage of ownership at
	Country of		December 31,
Company	Organization	Main activity	2008			2007			2006
Ternium S.A.	Luxembourg	Holding of investments in flat and long steel manufacturing and distributing companies		100.00	%		100.00	%		100.00	%
Hylsamex S.A. de C.V. (1)	Mexico	Holding company		—			88.23	%		88.22	%
Siderar S.A.I.C.	Argentina	Manufacturing and selling of flat steel products		60.93	%		60.93	%		60.93	%
Sidor C.A. (2)	Venezuela	Manufacturing and selling of steel products		—			56.38	%		56.38	%
Ternium Internacional S.A.	Uruguay	Holding company and marketing of steel products		100.00	%		100.00	%		100.00	%
Ylopa — Servicos de Consultadoria Lda. (3)	Portugal	Participation in the debt restructuring process of Amazonia and Sidor C.A.		94.38	%		95.66	%		95.66	%
Consorcio Siderurgia Amazonia S.L.U. (formerly Consorcio Siderurgia Amazonia Ltd.) (4)	Spain	Holding of investments in Venezuelan steel companies		94.38	%		94.38	%		94.38	%
Fasnet International S.A.	Panama	Holding company		100.00	%		100.00	%		100.00	%
Alvory S.A.	Uruguay	Holding of investment in procurement services companies		100.00	%		100.00	%		100.00	%
Comesi San Luis S.A.I.C. (5)	Argentina	Production of cold or hot rold prepainted, formed and skelped steel sheets		—			61.32	%		61.32	%
Impeco S.A. (6)	Argentina	Manufacturing of pipe products		60.96	%		60.93	%		60.93	%
Inversiones Basilea S.A. (6)	Chile	Purchase and sale of real estate and other		60.93	%		60.93	%		60.93	%
Prosid Investments S.C.A.(6)	Uruguay	Holding company		60.93	%		60.93	%		60.93	%
Ternium Internacional España S.L.U. (7)	Spain	Marketing of steel products		100.00	%		100.00	%		100.00	%
Ternium International Ecuador S.A. (8)	Ecuador	Marketing of steel products		100.00	%		100.00	%		100.00	%
Ternium International USA Corporation (8)	USA	Marketing of steel products		100.00	%		100.00	%		100.00	%
Ternium Internationaal B.V. (8)	Netherlands	Marketing of steel products		100.00	%		100.00	%		100.00	%
Ternium Internacional Perú S.A.C. (8)	Peru	Marketing of steel products		100.00	%		100.00	%		100.00	%
Ternium International Inc.	Panama	Marketing of steel products		100.00	%		100.00	%		100.00	%
Hylsa S.A. de C.V. (9)	Mexico	Manufacturing and selling of steel products		88.71	%		88.23	%		88.22	%
Ferropak Comercial S.A. de C.V. (9)	Mexico	Scrap company		88.71	%		88.23	%		88.22	%


			Percentage of ownership at
	Country of		December 31,
Company	Organization	Main activity	2008			2007			2006
Ferropak Servicios S.A. de C.V. (9)	Mexico	Services		88.71	%		88.23	%		88.22	%
Galvacer America Inc (9)	USA	Distributing company		88.71	%		88.23	%		88.22	%
Galvamet America Corp (9)	USA	Manufacturing and selling of insulates panel products		88.71	%		88.23	%		88.22	%
Transamerica E. & I. Trading Corp (9)	USA	Scrap company		88.71	%		88.23	%		88.22	%
Galvatubing Inc. (9)	USA	Manufacturing and selling of pipe products		88.71	%		88.23	%		88.22	%
Las Encinas S.A. de C.V. (9)	Mexico	Exploration, explotation and pelletizing of iron ore		88.71	%		88.23	%		88.22	%
Técnica Industrial S.A. de C.V. (9)	Mexico	Services		88.71	%		88.23	%		88.22	%
Consorcio Minero Benito Juarez Peña Colorada S.A.de C.V. (10)	Mexico	Exploration, explotation and pelletizing of iron ore		44.36	%		44.12	%		44.11	%
Peña Colorada Servicios S.A. de C.V. (10)	Mexico	Services		44.36	%		44.12	%		44.11	%
Ternium Treasury Services S.A.	Uruguay	Financial Services		100.00	%		100.00	%		—
Ternium Treasury Services B.V	Holanda	Financial Services		100.00	%		100.00	%		—
Servicios Integrales Nova de Monterrey S.A. de C.V. (11)	Mexico	Medical and Social Services		66.09	%		65.73	%		—
Ternium Mexico S.A. de C.V. (formerly Grupo Imsa S.A.B. de C.V.)	Mexico	Holding company		88.71	%		100.00	%		—
Imsa Acero S.A. de C.V. (12)	Mexico	Holding company		88.71	%		100.00	%		—
Enermex S.A. de C.V. (12)	Mexico	Holding company		88.71	%		100.00	%		—
Sefimsa S.A. de C.V. (12)	Mexico	Financial Services		88.71	%		100.00	%		—
Ecore Holding S. de R.L. de C.V. (12)	Mexico	Holding company		88.71	%		100.00	%		—
Neotec L.L.C. (12)	USA	Holding company		88.71	%		100.00	%		—
Treasury Services L.L.C. (12)	USA	Financial Services		88.71	%		100.00	%		—
APM, S.A. de C.V. (12)	Mexico	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Acedor, S.A. de C.V. (12)	Mexico	Holding company		88.71	%		100.00	%		—
Empresas Stabilit S.A. de C.V. (12)	Mexico	Holding company		88.71	%		100.00	%		—
Acerus S.A. de C.V. (12)	Mexico	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Imsa Monclova S.A. de C.V. (12)	Mexico	Services		88.71	%		100.00	%		—


			Percentage of ownership at
	Country of		December 31,
Company	Organization	Main activity	2008			2007			2006
Imsamex Ecuador S.A. (12)	Ecuador	Marketing of steel products		88.71	%		100.00	%		—
Industrias Monterrey S.A. (12)	Guatemala	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Corporativo Grupo Imsa S.A. de C.V. (12)	Mexico	Services		88.71	%		100.00	%		—
Industrias Monterrey S.A. de C.V. (12)	Mexico	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Ternium USA Inc. (formerly Imsa Holding Inc.) (12)	USA	Holding company		88.71	%		100.00	%		—
Industria Galvanizadora S.A. (12)	Guatemala	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Imsa Americas Inc. (12)	USA	Marketing of steel products		88.71	%		100.00	%		—
Imsa Caribbean Inc. (12)	Puerto Rico	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Ternium Internacional de Colombia S.A. (formerly Imsa Colombia S.A.)	Colombia	Marketing of steel products		100.00	%		100.00	%		—
Imsa Andina S.A. (12)	Peru	Marketing of steel products		88.71	%		100.00	%		—
Multypanel de América S.A. (12)	Costa Rica	Manufacturing and selling of insulates panel products		88.71	%		100.00	%		—
Industria Galvanizadora S.A. (12)	Nicaragua	Manufacturing and selling of steel products		88.09	%		99,30	%		—
Industria Galvanizadora de Honduras S.A. de C.V. (12)	Honduras	Manufacturing and selling of steel products		88.00	%		99.20	%		—
Ternium Internacional El Salvador, S.A. de C.V. (formerly Industria Galvanizadora S.A. de C.V.) (12)	El Salvador	Manufacturing and selling of steel products		88.65	%		99.93	%		—
Industrias Monterrey S.A. (12)	Costa Rica	Manufacturing and selling of steel products		88.71	%		100.00	%		—
Dirken Company S.A. (13)	Uruguay	Holding Company		100.00	%		—			—
Secor- Servicios Corporativos S.A. (14)	Venezuela	Holding Company		93.44	%		—			—
Ternium Brasil S.A. (14)	Brazil	Holding Company		100.00	%		—			—


(1)		Effective April 1, 2008, it was merged with and into Ternium México, S.A. de C.V.

(2)		See Note 29 (ii).

(3)		Directly (85.62%) and indirectly through Prosid Investments S.C.A. (8.76%). Total voting rights held: 100.00%.

(4)		Indirectly through Ylopa — Serviços de Consultadoria Lda. Total voting rights held: 100.00%. On April 25, 2008, this subsidiary changed its domicile to Spain and continues its corporate existence under the laws of Spain.

(5)		As of December, 2008 it was merged with and into Impeco S.A.

(6)		Indirectly through Siderar S.A.I.C. Total voting rights held 100.00%.

(7)		Indirectly through Dirken Company S.A. Total voting rights held 100.00%.

(8)		Indirectly through Ternium Internacional S.A. Total voting rights held 100.00%.

(9)		Indirectly through Ternium Mexico, S.A. de C.V. Total voting rights held: 99.92%.

(10)		Indirectly through Ternium Mexico, S.A. de C.V. Total voting rights held: 50.00%. Consolidated under the proportionate consolidation method (see Note 2 (ii)).

(11)		Indirectly through Ternium Mexico, S.A. de C.V. Total voting rights held: 74.44%.

(12)		Indirectly through Ternium Mexico, S.A. de C.V. (see Note 3 (a)). Effective April 1, 2008 Siderar exchanged all of its shares in Hylsamex for shares in Ternium Mexico, S.A. de C.V., thus reducing Ternium’s indirect participation in all of Ternium Mexico’s subsidiaries.

(13)		Incorporated during 2008, as a result of a spin off of Ternium Internacional S.A.

(14)		Incorporated during 2008.