Aerocrine announces supplement to prospectus

Not for publication, release or distribution, directly or indirectly, in or into the United States, Canada, Australia, Hong Kong, Singapore, South Africa, Japan or New Zealand.

Aerocrine announces a supplement to the prospectus that was made public on 17 April 2012. The supplement has been prepared as a result of the following three events;

• Aerocrine announced on 30 April 2012, after several years of litigation, that the bankruptcy court overseeing the claims to the Apieron Inc estate has authorised the trustee to pay Aerocrine USD 1.3 million in a compromise against claims.

• On 3 May 2012, Aerocrine published its interim report for the period January – March 2012.

• Aerocrine announced on 4 May 2012 that the company has decided to call for conversion of the company’s convertible bonds 2010/2015.

The supplement to the prospectus is available at www.aerocrine.com and www.remium.com and at Aerocrine’s offices, Sundbybergsvägen 9, SE-171 73 Solna, Sweden. The prospectus can also be ordered from Aerocrine by telephone +46 (0)8–629 07 80.

For further information, please contact:

Scott Myers, President and CEO of Aerocrine                                                        Michael Colérus, CFO

Tel: +46-(0)8-629 0780                                                                                                  Tel: +46-(0)8-629 0785

E-mail: scott.myers@aerocrine.com                                                                           E-mail: michael.colerus@aerocrine.com

About Aerocrine

Aerocrine AB (publ.) is a medical technology company focused on the improved management and care of patients with inflammatory airway diseases. As the pioneer and leader in the technology to monitor and manage airway inflammation, Aerocrine markets NIOX® Flex and NIOX MINO®. Both products enable fast and reliable management of airway inflammation and may therefore play a critical role in more effective diagnosis, treatment and follow-up of patients with inflammatory airway diseases such as asthma. Aerocrine is based in Sweden with subsidiaries in the US, Germany and the UK. Aerocrine’s shares were listed on the Stockholm Stock Exchange on 15 June 2007.

Aerocrine discloses the information provided in this press release pursuant to the Securities Markets Act. The information was provided for public release on 4 May 2012 at 4 pm CET.

This press release does not constitute an offer of any securities of Aerocrine. The rights issue is not directed to shareholders or other investors domiciled in the United States, Canada, Australia, Hong Kong, Singapore, South Africa, Japan or New Zealand, or in any other country where participation in the issue would require additional prospectuses, registration or other measures other than those pursuant to Swedish law or would conflict with regulations in such country. No shares, interim shares, subscription rights or other securities issued by Aerocrine have been or will be registered in accordance with the United States Securities Act of 1933, or in accordance with any securities legislation in any state of the United States or any province in Canada. Accordingly, no new shares, interim shares, subscription rights or other securities issued by Aerocrine may be transferred or offered for sale in the United States or Canada, other than in such exceptional cases that do not require registration. The rights issue is directed only at (i) persons who are outside the United Kingdom; (ii) investment professionals falling within Article 19(5) of the Financial Services and Markets Act 2000 (Financial Promotion) Order 2005 (as amended); or (iii) persons to whom it can otherwise lawfully be directed at.