Genmab — Director's Dealing 2008

Sep 2, 2008

REPORT PURSUANT TO SECTION 28a OF THE DANISH SECURITIES TRADING ACT

Copenhagen, Denmark; September 2, 2008 – Pursuant to Section 28a of the Danish Securities Trading Act, Genmab A/S (OMX: GEN) shall make public information on transactions by managerial employees and their related parties involving Genmab shares and related instruments, as follows:

Name: Ernst Schweizer Reason: Member of the Board of Directors Issuer: Genmab A/S ID code/ ISIN: DK0010272202 Description: Shares Transaction: Warrant Exercise Trading date: September 2, 2008 Market: OMX Nordic Exchange Copenhagen A/S Number: 44,500 Value: DKK 4,149,000

Name: Ernst Schweizer Reason: Member of the Board of Directors Issuer: Genmab A/S ID code/ ISIN: DK0010272202 Description: Shares Transaction: Sale Trading date: September 2, 2008 Market: OMX Nordic Exchange Copenhagen A/S Number: 44,500 Value: DKK 14,863,000

About Genmab A/S

Genmab is a leading international biotechnology company focused on developing fully human antibody therapeutics for unmet medical needs. Using cutting-edge antibody technology, Genmab's world class discovery, development and manufacturing teams have created and developed an extensive pipeline of products for potential treatment of a variety of diseases including cancer and autoimmune disorders. As Genmab advances towards a commercial future, we remain committed to our primary goal of improving the lives of patients who are in urgent need of new treatment options. For more information on Genmab's products and technology, visit www.genmab.com.

Genmab A/S Tel: +45 7020 2728 Stock Exchange Release no. 40/2008 Toldbodgade 33 Fax: +45 7020 2729 Page 1/2

REPORT PURSUANT TO SECTION 28a OF THE DANISH SECURITIES TRADING ACT

This press release contains forward looking statements. The words "believe", "expect", "anticipate", "intend" and "plan" and similar expressions identify forward looking statements. Actual results or performance may differ materially from any future results or performance expressed or implied by such statements. The important factors that could cause our actual results or performance to differ materially include, among others, risks associated with product discovery and development, uncertainties related to the outcome and conduct of clinical trials including unforeseen safety issues, uncertainties related to product manufacturing, the lack of market acceptance of our products, our inability to manage growth, the competitive environment in relation to our business area and markets, our inability to attract and retain suitably qualified personnel, the unenforceability or lack of protection of our patents and proprietary rights, our relationships with affiliated entities, changes and developments in technology which may render our products obsolete, and other factors. For a further discussion of these risks, please refer to the section "Risk Management" in Genmab's Annual Report, which is available on www.genmab.com. Genmab does not undertake any obligation to update or revise forward looking statements in this press release nor to confirm such statements in relation to actual results, unless required by law.

Genmab®; the Y-shaped Genmab logo®; HuMax®; HuMax-CD4®; HuMax-CD20®; HuMax-EGFr™; HuMax-IL8™; HuMax-TAC™; HuMax-HepC™; HuMax-CD38™; HuMax-CD32b™ and UniBody® are all trademarks of Genmab A/S.

Contact: Helle Husted, Sr. Director, Investor Relations T: +45 33 44 77 30; M: +45 25 27 47 13; E: hth@genmab.com

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