1. In order to assess the prevalence of concurrent use of more than one major psychotropic drug (polypsychopharmacy) in out-patients, a prescription database study was conducted in the Odense area for a period of 2 years. 2. During the index period 5.12% of the inhabitants purchased major psychotropic drugs. Of these, 14% had a period of polypsychopharmacy recorded. The age-specific prevalence of users increased with age, the prevalence for over 90 years of age was 18%. Sixty-seven per cent of the psychotropic drug users were women. 3. For neuroleptic and antidepressant users, about 20% were subject to polypsychopharmacy, for lithium 61%. The most prevalent combination was neuroleptics-neuroleptics. In none of the 10 most prevalent combinations were the mean daily doses significantly lower on polypsychopharmacy compared with single drug regimens, in two they were higher. 4. Polypsychopharmacy with psychotropic drugs was frequent in out-patients. In polypsychopharmacy daily doses were not lowered in order to limit side effects.