PRESS RELEASE: BB BIOTECH: Positive performance in the third quarter 2009 Corporate news announcement processed and transmitted by Hugin AS. The issuer is solely responsible for the content of this announcement. = =

Quarterly Report as at September 30, 2009

During the third quarter 2009, BB BIOTECH's portfolio companies achieved a positive performance in line with the broad biotechnology index, with the Net Asset Value (NAV) increasing by 7.2% in CHF. BB BIOTECH's share price closed the quarter at CHF 77.95, up 12.2% compared to the second quarter 2009. In Germany, it closed at EUR 51.42, up 10.6% compared to the previous quarter. The difference between the share price and the Net Asset Value of BB BIOTECH decreased at the end of the third quarter to 19.2% down from 22.8% at the end of second quarter. We will continue our measures to control the discount between the share price and Net Asset Value and as such we have initiated the sixth share buyback program in September.

BB BIOTECH's core positions, Actelion, Celgene, Gilead and Vertex, progressed in line with our assumptions. Actelion delivered continued strong growth of its PAH franchise with the US FDA broadening the Tracleer label to include treatment for less advanced PAH patients. Clinical data for Almorexant, a potential new therapy for insomnia, is the key milestone for the company by year end.

Celgene announced that a Phase III trial testing its flagship product, Revlimid, for the treatment of patients with newly diagnosed multiple myeloma ineligible for stem cell transplantation, was stopped early as it met its primary efficacy end point at the first interim analysis. The positive results should allow Celgene to expand the label for Revlimid, currently approved only for relapsed/refractory multiple myeloma patients, to the first-line setting, increasing the sales potential for Revlimid.

Gilead reported positive earnings numbers, driven by continued strength of its HIV products Atripla and Truvada. The company announced a collaboration with Johnson & Johnson (Tibotec) to develop a fixed-dose combination of Truvada with Tibotec's non-nucleoside reverse transcriptase inhibitor (NNRTI) TMC278. We believe this has the potential to replace Sustiva, the NNRTI component of Atripla. A successful launch could solidify Gilead's leading position in HIV therapy and could boost Gilead's earnings.

At the American Association for the Study of Liver Disease meeting in November, we expect Vertex to present results from a Phase II trial with Telaprevir, its protease inhibitor for HCV. The study is comparing twice-daily dosing to three-times-daily dosing (already shown to be highly effective in Phase II trials) and we expect the cure rate between the two regimens to be comparable, providing a further advantage to patients. We also expect data on several early stage protease inhibitors in development from competitor companies. While one or more of these agents could be successful in the clinic, we believe the safety hurdle is high and they would come to market several years behind Telaprevir, which we expect to launch in 2011.

BB BIOTECH has initiated two new investment positions with Genzyme and Micromet. Genzyme is progressing well to resolve its manufacturing problems for its key product Cerezyme, approved for the treatment of a rare genetic lysosomal storage disorder called Gaucher's Disease. BB BIOTECH participated in the capital increase of Micromet. Micromet's lead clinical program is a bi-specific single-chain antibody targeting CD19 BiTE® for the treatment of lymphoma. Positive clinical data support the bi-specific antibody platform of Micromet. The positions in Rigel and The Medicines Company were sold, with BB BIOTECH realizing a significant gain on The Medicines Company of around CHF 109 mn over the entire investment period.

BB BIOTECH initiated its sixth share buyback program on September 16, 2009, acquiring 113 500 shares until the end of the third quarter. The shareholders confirmed the resolution of a sixth share buyback program at the extraordinary general assembly on July 6, 2009 to repurchase and cancel up to 1.8225 million of BB BIOTECH's registered shares, corresponding to 10% of total share capital. The reduction in the number of outstanding registered shares will increase earnings per share and should also reduce the discount between the market price and the reported Net Asset Value.

The ongoing debate on US healthcare reform is advancing with the uncertainty still weighing on the share performance of many healthcare companies. We think BB BIOTECH's portfolio is well balanced regarding possible healthcare reform risks towards potential changes to the portfolio companies' revenues and profits. Innovative and effective medicines will continue to achieve good pricing as well as reimbursement in the Western world, even in a cost conscious environment.

This is the composition of BB BIOTECH's Portfolio as at September 30, 2009 (in % of securities, rounded values):

CORE HOLDINGS Actelion 32.1% Gilead 17.6% Celgene 16.4% Vertex Pharmaceuticals 12.2%

SMALL PARTICIPATIONS Novo Nordisk 4.2% Zymogenetics 2.4% Biogen Idec 2.2% Roche Holding 1.9% Arena Pharmaceuticals 1.6% Basilea Pharmaceutica 1.4% Affymetrix 1.2% Genzyme 1.2% Micromet 1.0% Optimer Pharmaceuticals 0.8% Elan 0.7% NicOx 0.4% Incyte 0.4% Epigenomics 0.3% BioXell 0.2% Keryx Biopharmaceuticals 0.1% Clinuvel