Extemporaneous preparations are drugs that are compounded for individual patients or made in larger batches for stock‐keeping. This study aimed to analyse factors associated with the prescribing of such preparations in Sweden.Information was taken from the Swedish diagnosis and therapy survey for the time period October, 1986, to September, 1988, inclusive. This survey collects from a random sample of doctors the details of all prescriptions they write during one week, as well as all corresponding diagnoses. The present study analysed extemporaneous prescriptions and the characteristics of doctors issuing them.Of the 2,142 doctors who contributed prescriptions to the survey, 19 per cent wrote at least one prescription for an extemporaneous preparation. Young patients obtained such preparations more than older patients. Proportionately fewer of the youngest doctors prescribed them. Dermatologists prescribed extemporaneous preparations much more commonly than other doctors, and most of the preparations concerned were dermatologicals. The most common diagnosis for the prescribing of these preparations was contact eczema, with psoriasis second. The findings suggest that the prescribing of extemporaneous preparations is established and continuing and not just a feature of obsolete practice. However, the appropriateness of these products should be further analysed and assessed to ensure that they are clinically and pharmaceutically safe and effectiv