Additional Disclosure to be added to the Platinum Underwriters Holdings, Ltd.
  Form 10-K in response to clarifications requested by Ms. Dana Hartz and Mr.
     Joseph Roesler of the Staff of the Securities and Exchange Commission.


     Additional disclosure to be added in response to first clarification
request:

The time lag involved in the process of reporting premiums is shorter than the
lag in reporting losses. Premiums are generally reported within two years. The
net impact on the results of operations of changes in estimated premiums is
reduced by the losses and acquisition expenses related to such premiums. When
estimating premiums written and earned, each of the Company's reinsurance
subsidiaries segregates business into classes by type of coverage and type of
contract (approximately 80 classes). Within each class, business is further
segregated by the year in which the contract incepted (the "underwriting year"),
starting with 2002. Estimates of WBNR and EBNR are made for each class and
underwriting year. Premiums are estimated based on ceding company estimates and
the Company's own judgment after considering factors such as the ceding
company's historical premium versus projected premium, the ceding company's
history of providing accurate estimates, anticipated changes in the marketplace
and the ceding company's competitive position therein, reported premiums to date
and the anticipated impact of proposed underwriting changes. The appropriateness
of the premium estimates is evaluated in light of the actual premium reported by
the ceding companies and any adjustments to these estimates are accounted for as
changes in estimates and are reflected in results of operations in the period in
which they are made. The initial estimates of premiums derived by the Company's
underwriting function in respect of 2004 year-end were reviewed based upon the
foregoing considerations. The cumulative impact of this review was to reduce the
estimate by approximately $56 million or 10% of reinsurance premiums receivable
at December 31, 2004. At December 31, 2004, the Company recorded reinsurance
premiums receivable of $580,048,000. As an illustration, the Company had one
contract which, at December 31, 2004, represented approximately $88 million of
its total reinsurance premiums receivable. With respect to that contract, the
Company reduced reinsurance premiums receivable by approximately $20 million
because it did not expect the ceding company to meet its production estimates or
to achieve its estimated rate increases. The Company believes that it reasonably
could have made an adjustment of between $0 and $20 million with respect to that
contract at December 31, 2004. Had it made a $0 adjustment, the reinsurance
premiums receivable for that contract at December 31, 2004 would have been $108
million. It made the $20 million adjustment, resulting in reinsurance premiums
receivable for that contract of $88 million. While an adjustment of greater than
$20 million is possible with respect to that contract, the Company does not
consider such circumstance to be reasonably likely. Reinsurance premiums
receivable under a particular contract can vary significantly from estimates
derived from the Company's underwriting function depending upon its assessment
of the production and rate changes likely to be achieved by the ceding company.

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     Additional disclosure to be added in response to second clarification
request:

         Generally, North American casualty excess business has the longest
pattern of reported losses and therefore the greatest uncertainty. IBNR for
these classes at December 31, 2004 was $447 million which was 39% of the total
IBNR for the Company at that date. Because North American casualty excess
business has the greatest uncertainty, the Company would not consider a variance
of five percentage points from the initial expected loss ratio to be unusual. As
an example, a change in the initial expected loss ratio from 65% to 70% would
result in an increase of the IBNR for these classes by $37 million. This equates
to approximately 7% of the liability for total unpaid losses and LAE for these
classes at December 31, 2004. As another example, if the estimated pattern of
reported losses was accelerated by 5% the IBNR for these classes would decrease
by $2 million which is less than 1%. Because the Company believes the two most
important inputs to the reserve estimation methodologies described above are the
initial expected loss ratio and the estimated pattern of reported losses, the
Company has selected these two inputs as the basis for the sensitivity analyses
in this paragraph.

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     Additional disclosure to be added in response to third clarification
request:

Due to the time lag inherent in the reporting of premiums by ceding companies, a
significant portion of amounts included as premiums written and premiums earned
represents estimated premiums and are not currently due based on the terms of
the underlying contracts. Earned premiums, including EBNR, are a measure of
exposure to losses, LAE and acquisition expenses. Consequently, when previous
estimates of premiums earned are increased or decreased, the related provisions
for losses and LAE and acquisition costs previously recorded are also increased
or decreased.