A prospective survey of drug-induced diseases has been performed along a one year period in a department of dermatology. Among the 550 patients hospitalized during this period for a cutaneomucous event, a drug-induced disease is pointed out in 30 of them (5.6 p. cent). The use of algorithm allows the establishment of the cause-effect relationship; the relative value of literature data and the role of three main predisposing factors (age, allergic antecedents, polymedication) are insisted upon. Three categories of drugs are primarily implicated: cardiovascular, antiinflammatory and antiinfectious drugs. The most commonly observed events are erythrodermia and allergic phenomena. If favorable evolution is usual, one fatal adverse drug reaction is firmly established in our series. Such a survey would lead to preventive attitudes.