SUPPLEMENT DATED FEBRUARY 4, 2000, TO
                      THE PROSPECTUS DATED MAY 1, 1999, FOR
                        FIRSTLINE VARIABLE UNIVERSAL LIFE
                                       AND
                      FIRSTLINE II VARIABLE UNIVERSAL LIFE
                 FLEXIBLE PREMIUM VARIABLE LIFE INSURANCE POLICIES
                                    ISSUED BY
                    SECURITY LIFE OF DENVER INSURANCE COMPANY
                                     AND ITS
                        SECURITY LIFE SEPARATE ACCOUNT L1

THIS SUPPLEMENT UPDATES CERTAIN INFORMATION CONTAINED IN YOUR PROSPECTUS DATED
MAY 1, 1999 AS SUPPLEMENTED ON SEPTEMBER 16, 1999. PLEASE READ IT CAREFULLY AND
KEEP IT WITH YOUR PROSPECTUS FOR FUTURE REFERENCE.

The information previously added after the first sentence of the second
paragraph in the "Policy Issuance" subsection on page 20 is hereby deleted and
replaced in its entirety as follows:

          "If we receive your initial premium after we approve your
          policy for issue, the investment date is the date we receive
          your initial premium."


                        * * * * * * * * * * * * * * * * *


The information previously added to the end of the last paragraph in the "Policy
Issuance" subsection on page 20 is hereby deleted and replaced in its entirety
as follows:

          "If the policy date is earlier, we charge monthly deductions
          from the date we receive your initial premium. The policy
          date is determined one of three ways:

          1.   the date you designate on your application, subject to
               our approval; or

          2.   the back-date of the policy to save age, subject to our
               approval and state law.

          3.   If there is no designated date or back-date, the policy
               date is:
                  o  the date all underwriting and administrative
                     requirements have been met if we receive your
                     initial premium before we issue your policy; or
                  o  the date we receive your initial premium, if it
                     is after we approve your policy for issue."


                        * * * * * * * * * * * * * * * * *


                                   Page 1 of 2




The second and third sentenceS of the third paragraph in the "Allocation of Net
Premiums" subsection of the "Premiums" section on page 22 of FirstLine and
FirstLine II are hereby deleted and replaced in their entirety as follows:

          "If your state requires return of your premium during the
          free look period, we invest amounts you have designated for
          the variable division in the Fidelity VIP Money Market
          Portfolio for a period ending on the earlier of your state's
          free look period plus:
             o  five days from mailing (deemed delivery time); or
             o  the date the policy was delivered to you, so long as
                we receive notice of the delivery date on our delivery
                receipt form at our Customer Service Center before the
                end of the deemed delivery time plus the free look
                period.

          At the end of this time period, we will allocate the amount
          you designated for the variable division among your chosen
          variable division portfolios, based on your most recent
          premium allocation instructions.

          If your state provides for return of account value during
          the free look period or no free look period, we invest
          amounts you designated for the variable division directly
          into your selected investment options."


                        * * * * * * * * * * * * * * * * *


The fourth paragraph through the end of the "Free Look Period or Right to
Examine Policy Period" subsection of the "General Policy Provisions" section on
pages 40 - 41 of FirstLine and pages 39 - 40 of FirstLine II is hereby deleted
in its entirety.


                        * * * * * * * * * * * * * * * * *

                                   Page 1 of 2