deCODE has discovered a gene with certain variations that predispose to obesity and others that predispose to thinness

Reykjavik, ICELAND, September 30, 2003 — deCODE genetics (Nasdaq/Nasdaq Europe:DCGN) today announced that it has achieved a milestone under its alliance with Merck to develop novel treatments for obesity.

Through genotypic analysis involving more than 1000 women participants in its obesity program, deCODE scientists have isolated a gene which in one form predisposes to obesity and in another form predisposes to thinness. The companies are using this information in their drug discovery program. deCODE receives a milestone payment for the identification of the gene.

“These are exciting results that suggest we have identified key markers within a pathway involved in the regulation of body weight in women,” said Kari Stefansson, CEO of deCODE. “Obesity and thinness are two sides of the same coin, and with our partners at Merck we are working to identify the best targets for therapeutic intervention within this pathway as well as compounds that are effective against these targets. This is an important step towards developing new drugs that can treat obesity, perhaps by utilizing the body’s own mechanisms for promoting and maintaining thinness.”

About deCODE

deCODE is using population genetics to create a new paradigm for healthcare. With its uniquely comprehensive population data, deCODE is turning research on the genetic causes of common diseases into a growing range of products and services — in gene and drug discovery, DNA-based diagnostics, pharmacogenomics, bioinformatics, and clinical trials. deCODE’s pharmaceuticals group, based in Chicago, and deCODE’s biostructures group, based in Seattle, conduct downstream development work on targets derived from deCODE’s proprietary research in human genetics as well as contract service work for pharmaceutical and biotechnology companies. deCODE is delivering on the promise of the new genetics.SM Visit us on the web at www.decode.com.

Any statements contained in this presentation that relate to future plans, events or performance are forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. These forward-looking statements are subject to a number of risks and uncertainties that could cause actual results to differ materially from those described in the forward-looking statements. These risks and uncertainties include, among others, those relating to technology and product development, integration of acquired businesses, market acceptance, government regulation and regulatory approval processes, intellectual property rights and litigation, dependence on collaborative relationships, ability to obtain financing, competitive products, industry trends and other risks identified in deCODE’s filings with the Securities and Exchange Commission. deCODE undertakes no obligation to update or alter these forward-looking statements as a result of new information, future events or otherwise.