The authors reviewed the drug side effects observed in their ward during the 5 last years (1988-92). These alleged effects occurred at a very low incidence, 3 per cent, (116 cases on 3809 hospitalizations). As mentioned in the literature, the occurrence was higher in females (60 per cent), than in males. The age seemed not to be a risk factor in that population, the mean age being 44 for the men and 45 for the women. All side effects disappeared after decreasing or stopping the suspected drug. In 6 cases the suspected drug was not a psychotropic agent. The authors presented some of the more often reported cases, and some of the more recently known, such as extrapyramidal side effects with antidepressants, increase of the libido with serotonergic antidepressants. The problem fo polytherapy is discussed. In half (59/116) of the cases there was a psychotropic association. The side effect may be due to a pharmacokinetic interaction in 16 cases, either with enzymatic inhibitors like dextropropoxyphene, valpromide, valproic acid, fluvoxamine and fluoxetine, or with enzymatic inducers like carbamazepine. The authors compared the side effects of the antidepressants mainly used in their ward (amitriptyline, clomipramine, fluvoxamine and fluoxetine).