<PAGE>
SUPPLEMENT DATED OCTOBER 26, 1998, TO
THE PROSPECTUS DATED MAY 1, 1998
FIRSTLINE VARIABLE UNIVERSAL LIFE
A FLEXIBLE PREMIUM VARIABLE LIFE INSURANCE POLICY
ISSUED BY
SECURITY LIFE OF DENVER INSURANCE COMPANY
AND
SECURITY LIFE SEPARATE ACCOUNT L1
THIS SUPPLEMENT UPDATES CERTAIN INFORMATION CONTAINED IN YOUR PROSPECTUS. PLEASE
READ IT CAREFULLY AND KEEP IT WITH YOUR PROSPECTUS FOR FUTURE REFERENCE.
The first sentence in the "Policy Loans" section on page 28 is changed to read:
"At any time after the first policy Monthly Processing Date, or as
otherwise required by law, the Owner may borrow against the Policy by using
it as security for a loan."
Effective July 6, 1998, INVESCO Funds Group, Inc. ("IFG"), the investment
adviser to INVESCO Variable Investment Funds, Inc., changed the arrangements by
which it voluntarily absorbs certain expenses of the INVESCO VIF - Total Return
Portfolio, INVESCO VIF - Industrial Income Portfolio, INVESCO VIF - High Yield
Portfolio, INVESCO VIF - Utilities Portfolio and INVESCO VIF - Small Company
Growth Fund. See Pages 37 - 39 of the prospectus. The annual expenses of
these Portfolios, restated to reflect these changes, are as follows:
<TABLE>
<CAPTION>
PORTFOLIO INVESTMENT OTHER EXPENSES TOTAL
MANAGEMENT PORTFOLIO
FEE EXPENSES
======================================================================
<S> <C> <C> <C>
INVESCO VIF - 0.75% 0.40% 1.15%
Total Return Portfolio
INVESCO VIF - 0.75% 0.40% 1.15%
Industrial Income Portfolio
INVESCO VIF - High 0.60% 0.45% 1.05%
Yield Portfolio
INVESCO VIF - 0.60% 0.55% 1.15%
Utilities Portfolio
INVESCO VIF - Small 0.75% 0.50% 1.25%
Company Growth
Portfolio
</TABLE>
* * *
The illustrations of death benefits, account values and surrender values, and
accumulated premiums included on pages 49 - 56 of the prospectus reflect, among
other policy fees, charges, and costs, the simple average of total Portfolio
expenses for all Portfolios available through the Policy. Taking into account
the changes affecting the INVESCO VIF Portfolios described above, this simple
average increases from .7909 to .8387%.
<PAGE>
The third paragraph in the "Distribution of Policies" section on pages 47 - 48
is deleted and replaced in its entirety as follows:
"Under these selling agreements, we pay a distribution allowance to the
other broker-dealers, which in turn pay commissions to the Registered
Representative who sells this Policy. The distribution allowance may equal
an amount up to 95% of the first Target Premium paid and 4% of premiums
paid in excess of the first Target Premium. For Policy years two through
ten, the allowance may equal an amount up to 4% of premiums paid in excess
of the first Target Premium, and for subsequent Policy years 2% of premiums
paid. Broker-dealers may also receive annual renewal compensation of up to
0.10% of the Net Account Value beginning in the eleventh policy year or
after the Owner pays more than the guideline single premium determined in
accordance with the Federal income tax law definition of life insurance,
whichever is earlier. Compensation arrangements may vary among broker-
dealers and depend on particular circumstances. In addition, we may pay
override payments, expense allowances, bonuses, special marketing fees,
wholesaler fees, and training allowances. Registered Representatives who
meet specified production levels may qualify, under our sales incentive
programs, to receive non-cash compensation such as expense-paid trips,
expense-paid educational seminars and merchandise."
