Disclosure of shareholdings

Pursuant to article 26 sec 1 WpHG BB BIOTECH AG, Vordergasse 3, 8200 Schaffhausen, Switzerland hereby reports that it decreased its holding in own shares as per July 25, 2007 to below the thresholds of 5% and 3% of the proportion of voting rights. 1 400 000 bearer shares, which were bought during the repurchase program and approved for cancellation at the Annual General Meeting of March 26, 2007, were cancelled in the commercial register as at July 25, 2007. The share capital of BB BIOTECH AG now consists of 22.5 mn fully paid bearer shares with a pair value of CHF 1.00 each. Pursuant to article 22 sec 1 clause 1 no 1 WpHG 6.03% of the proportion of voting rights (a total of 1 356 148 bearer shares), which are held through the wholly-owned subsidiary Biotech Target N.V., Snipweg 26, Curaçao, Netherlands Antilles, need to be added to the voting rights of BB BIOTECH AG. BB BIOTECH AG does not hold any own shares as at July 25, 2007. For further information please contact: Bellevue Asset Management AG, Seestrasse 16, 8700 Küsnacht, Switzerland Adrian Bruengger or Dr. Christian Lach, Tel. +41 44 267 67 00 --- End of Message --- BB BIOTECH AG Vordergasse 3 Schaffhausen Switzerland WKN: 888509; ISIN: CH0001441580; Index: SBIOM, IGSP, SLIFE; Listed: Investment Companies in SWX Swiss Exchange;