OBJECTIVE--To determine the prevalence of continuous use of oral steroids in the general population, the conditions for which they are prescribed, and the extent to which patients taking oral steroids are taking treatment to prevent osteoporosis. DESIGN--A cross sectional study with a four year retrospective review of drug treatment. SETTING--Eight large general practices in central and southern Nottinghamshire. SUBJECTS--A population of 65,786 patients (52% women) registered with a general practitioner during 1995. RESULTS--303 patients (65% (197) women) aged 12-94 years were currently taking "continuous" (for at least three months) oral corticosteroid treatment. This figure represents 0.5% of the total population and 1.4% (245/17 114) of patients aged 55 years or more (1.7% (166/9601) of women). The usual steroid was prednisolone (97% (294/303)), the mean dose was 8.0 mg/day, and the median duration of oral steroid treatment determined in 149 patients was three years. The most common conditions for which continuous oral steroids were prescribed were rheumatoid arthritis (23% (70)), polymyalgia rheumatica (22% (66)), and asthma or chronic obstructive airways disease (19% (59)). Only 41 (14%) of the 303 patients taking oral steroids had received treatment for the prevention of osteoporosis over the past four years. Although 37 of the 41 patients were women, only 10% (18/181) of the women over 45 years taking continuous oral corticosteroids were currently taking hormone replacement therapy. CONCLUSIONS--If our figures are typical then they suggest that over 250,000 people in the United Kingdom are taking continuous oral steroids and that most of these are taking no prophylaxis against osteoporosis.