<PAGE>
SUPPLEMENT DATED OCTOBER 26, 1998, TO
THE PROSPECTUS DATED MAY 1, 1998
FIRSTLINE II 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 27 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 - High Yield
Portfolio, INVESCO VIF - Industrial Income Portfolio, INVESCO VIF - Small
Company Growth Fund, INVESCO VIF Total Return Portfolio, and INVESCO VIF -
Utilities Portfolio. See Pages 35 - 37 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 - High 0.60% 0.45% 1.05%
Yield Portfolio
INVESCO VIF - 0.75% 0.40% 1.15%
Industrial Income
Portfolio
INVESCO VIF - Small 0.75% 0.50% 1.25%
Company Growth Fund
INVESCO VIF - Total 0.75% 0.40% 1.15%
Return Portfolio
INVESCO VIF - 0.60% 0.55% 1.15%
Utilities Portfolio
</TABLE>
* * *
The illustrations of death benefits, account values and surrender values, and
accumulated premiums included on pages 47 - 54 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 .07907% to .8387%.
<PAGE>
The third paragraph in the "Distribution of the Policies" section on pages 45 -
46 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. For premiums paid in
excess of the first Target Premium, the distribution allowance may equal an
amount up to 4% in policy years one through ten, and 2% in subsequent
years. Broker-dealers may also receive annual renewal compensation of up
to 0.15% of the Net Account Value beginning in the eleventh Policy year.
Compensation arrangements may vary among broker-dealers and depend on
particular circumstances. In addition, we also 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."
The third and fourth sentences of the first paragraph in the "Partial
Withdrawals" section on page 28 are deleted and replaced in their entirety as
follows:
"We may impose requirements on Partial Withdrawals as necessitated by our
administrative system. For example, we may require that requests be a
specified dollar amount rather than a percentage."
