Following the announcement in 1949 in the USA that cortisone offered rheumatoid arthritis sufferers effective treatment for their crippling disease, the Ministry of Health came under considerable pressure from the medical profession and the public to make cortisone available in Britain. The Ministry, therefore, urged British companies to start manufacturing cortisone. Among the several pharmaceutical firms responding to the Ministry’s request, Glaxo’s expertise in the field of vitamins gave them a head start. This paper describes the varied and flexible strategy (...) that enabled Glaxo to maintain this head start, and the scientific and technical capabilities which the company subsequently built up, enabling them to dominate the market for corticosteroids in Britain.Among the drugs to emerge out of the Glaxo project to manufacture cortisone, which began in 1950 and later became a wider R&D programme on steroids, was the topical steroid Betnovate, launched in 1963, which remains a best-seller today. However, although it led to successful new products, Glaxo’s programme had limitations. The paper identifies a missed opportunity, in the shape of the biosynthetic route to steroid drugs, often considered as a milestone in the development of the new biotechnology. Whether or not this missed opportunity proved costly to the company is uncertain. However, it illustrates the role of technological path-dependence, and the importance of the integration between different scientific disciplines, in this case chemistry and biology, in pharmaceutical innovation. (shrink)