Leiden, The Netherlands, May 23, 2001- Crucell N.V. (NASDAQ: CRXL, Euronext Amsterdam: CRXL) today announced that it has developed and tested a new, improved and larger phage antibody-display library of human antibody fragments, for target discovery and the development of antibody based therapeutics.

This library is part of Crucell's MAbstractTM technology to discover novel targets on disease-associated cells and generate fully human monoclonal antibodies against those targets in the areas of cancer, chronic inflammation, and cardiovascular disease. The library is employed to search for novel targets that are specifically present on disease-associated cells using a proprietary subtraction method of selection. The new library extends the versatility of the selection procedures for therapeutic human antibodies, and now contains around 50 billion different antibody fragments, which makes it one of the most comprehensive phage antibody-display libraries in existence.

"We are proud to have developed this new library, that includes features that will further enhance and accelerate our MAbstractTM program for the identification of novel targets and hence the development of biopharmaceuticals,' says Dr. Ton Logtenberg, Chief Scientific Officer of Crucell. "Compared to 4 previous libraries that we have constructed, this new library is not only improved in its capacity to identify new targets, it also contains ten times more human antibody fragments.'

About MAbstractTM
MAbstractTM is Crucell's phage antibody display library and related target discovery and antibody engineering technology to generate fully human monoclonal antibodies against disease-associated targets. The MAbstractTM technology yields targets on disease-associated cells, which Crucell believes cannot be found with conventional genomics or proteomics approaches. This enables Crucell to discover its own proprietary drug targets. The human antibodies generated by MAbstractTM against those drug targets are manufactured to high yields using Crucell's human cell line expression platform PER.C6TM, creating huMADETM antibodies, without any animal elements or modifications.

About Crucell
Crucell is a leading biotechnology company focused on the development of huMADETM biopharmaceuticals (human antibody-based therapeutics for treatment of cancer and inflammatory diseases; vaccines for the prevention and treatment of influenza and other infectious diseases) and on the discovery of unique drug targets on diseased cells.

Crucell's two broadly applicable human technology platforms form the basis for this. The first is a human cell line expression platform, PER.C6TM, on which a wide range of biopharmaceuticals can be developed and manufactured, such as vaccines, antibodies, therapeutic proteins and gene therapy products. The second technology is called MAbstractTM, a set of tools based on phage antibody-display libraries and proprietary subtraction and selection technology, to discover novel drug targets and develop human monoclonal antibodies as therapeutics for a variety of diseases. Biopharmaceuticals produced on Crucell's human PER.C6TM technology are called huMADETM.

Crucell makes its technologies available under exclusive or non-exclusive license agreements, and has currently signed 16 agreements with major pharmaceutical and biotechnology companies for its PER.C6TM technology.

Crucell currently employs approximately 130 people in its facilities in Leiden and Utrecht.

This press release contains forward-looking statements that involve inherent risks and uncertainties. We have identified certain important factors that may cause actual results to differ materially from those contained in such forward-looking statements. See our Registration Statement, as filed on Form F-1 with the U.S. Securities and Exchange Commission on October 26, 2000, (the "Registration Statement") and the section of the Registration Statement entitled "Risk Factors."

Crucell press release