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<TYPE>INTERNAL CONTROL RPT
<SEQUENCE>2
<FILENAME>NCEN_857621468300959.txt
<TEXT>
REPORT OF INDEPENDENT REGISTERED
PUBLIC ACCOUNTING FIRM

To the shareholders and the Board of Trustees of Tekla
Life Sciences Investors

In planning and performing our audit of the financial
statements of Tekla Life Sciences Investors (the "Fund")
as of and for the year ended September 30, 2020, in
accordance with the standards of the Public Company
Accounting Oversight Board (United States) (PCAOB),
we considered the Fund's internal control over financial
reporting, including controls over safeguarding
securities, as a basis for designing our auditing
procedures for the purpose of expressing our opinion on
the financial statements and to comply with the
requirements of Form N-CEN, but not for the purpose of
expressing an opinion on the effectiveness of the Fund's
internal control over financial reporting. Accordingly, we
express no such opinion.

The management of the Fund is responsible for
establishing and maintaining effective internal control
over financial reporting. In fulfilling this responsibility,
estimates and judgments by management are required
to assess the expected benefits and related costs of
controls. A fund's internal control over financial reporting
is a process designed to provide reasonable assurance
regarding the reliability of financial reporting and the
preparation of financial statements for external purposes
in accordance with generally accepted accounting
principles. A fund's internal control over financial
reporting includes those policies and procedures that (1)
pertain to the maintenance of records that, in reasonable
detail, accurately and fairly reflect the transactions and
dispositions of the assets of the fund; (2) provide
reasonable assurance that transactions are recorded as
necessary to permit preparation of financial statements
in accordance with generally accepted accounting
principles, and that receipts and expenditures of the fund
are being made only in accordance with authorizations
of management and trustees of the fund; and (3) provide
reasonable assurance regarding prevention or timely
detection of unauthorized acquisition, use, or disposition
of a fund's assets that could have a material effect on
the financial statements.

Because of its inherent limitations, internal control over
financial reporting may not prevent or detect
misstatements. Also, projections of any evaluation of
effectiveness to future periods are subject to the risk that
controls may become inadequate because of changes in
conditions or that the degree of compliance with the
policies or procedures may deteriorate.

A deficiency in internal control over financial reporting
exists when the design or operation of a control does not
allow management or employees, in the normal course
of performing their assigned functions, to prevent or
detect misstatements on a timely basis. A material
weakness is a deficiency, or a combination of
deficiencies, in internal control over financial reporting,
such that there is a reasonable possibility that a material
misstatement of the fund's annual or interim financial
statements will not be prevented or detected on a timely
basis.

Our consideration of the Fund's internal control over
financial reporting was for the limited purpose described
in the first paragraph and would not necessarily disclose
all deficiencies in internal control that might be material
weaknesses under standards established by the
PCAOB. However, we noted no deficiencies in the
Fund's internal control over financial reporting and its
operation, including controls for safeguarding securities,
that we consider to be a material weakness, as defined
above, as of September 30, 2020.

This report is intended solely for the information and use
of management and the Board of Trustees of the Fund
and the Securities and Exchange Commission and is not
intended to be and should not be used by anyone other
than these specified parties.

/s/ DELOITTE & TOUCHE LLP
Boston, Massachusetts
November 20, 2020






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