We have reviewed pharmaceutical advertisements in every available issue of the British Medical Journal (BMJ) in 12-month periods during 1955/6, 1965/6, 1975/6, and 1985/6. We have determined the amount of advertising, the therapeutic areas covered, and whether adverts reflected the large number of New Chemical Entities (NCEs) launched during that time. For each product we recorded the therapeutic indications, the marketing company, and the number of adverts appearing. The total number of products advertised fell from 340 in 1955/6 to 260 in 1965/6, 70 in 1975/6, and 16 in 1985/6. Advertisement numbers and companies advertising also fell. Antimicrobial drugs and cardiovascular drugs were the top products advertised over the 30 years, with respiratory, analgesic, and gastrointestinal drugs also in the top five. The number of different drugs advertised by individual companies fell from around eight per company in 1955/6 to one or two in 1985/6. There was good concordance between the most advertised therapeutic areas and NCEs entering the market. From the 1950s to the 1980s prescribers were extensively informed about pharmacological advances in therapeutics through BMJ advertisements. Many novel drugs that were advertised proved to be of lasting value. The Medicines Act 1968 introduced product licensing, regulations requiring demonstration of quality, efficacy, and safety, and restrictions on advertising. Subsequently many companies reduced their advertising or stopped altogether. Since advertising influences prescribing, and since antimicrobial drugs were the most commonly advertised products during 1955-86, we speculate that advertising, resulting in excess use, may have, at least partly, driven bacterial drug resistance.