During one week in 1985, 227 general practitioners (GPs) in the county of Aarhus, Denmark, recorded all their prescriptions of psychotropic drugs, amounting to 4,180 prescriptions for 3756 patients. There was great variation in the rate of prescribing among the GPs. The median number of prescribed defined daily doses per 1,000 registered patients per day was 84, and the corresponding median number of prescriptions per 1,000 patients per week was 14. There was a significantly lower rate of prescribing of psychotropic drugs by rural/small town GPs, compared with GPs in major cities (odds ratio, 0.84; 99% confidence limits, 0.77-0.91), after correction for differences in patients' age and sex. There were no differences in rate of prescribing among GPs in relation to size and type of practice, nor to the age and sex of the GP.