The adverse effects of a variety of drugs on psoriasis are well documented, and they generally result in aggravation of the disease. We report the case of a 75-year old man who developed a psoriatic erythroderma and a generalized pustular psoriasis two weeks after the beginning of an antimalarial treatment. The psoriasis responded poorly to etretinate alone, and an etretinate-methotrexate combination was needed to cure the patient. Some psoriasis vulgaris plaques persisted for six months after the acute complication. Thus, chloroquine should be entered in the list of drugs which may induce psoriasis.