The efficacy and safety of nimesulide (Aulin, CAS 51803-78-2) in a new pharmaceutical suppository form (200 mg) were assessed in a double-blind study versus paracetamol suppositories (500 mg). The study was conducted in a sample of aged in-patients suffering from viral or bacterial infections of upper and lower respiratory tract with fever. Thirty-nine patients were randomly assigned to treatment with nimesulide or paracetamol (18 nimesulide, 21 paracetamol). Both drugs, administered t.i.d. for 2 consecutive days followed by observation without therapy on the 3rd day, showed an adequate control of hyperpyrexia with significant reduction of body temperature from baseline. Tolerability was good for both drugs. Only one patient of the nimesulide group could not complete the study because of an adverse reaction consisting in cutaneous erythema with itching that regressed spontaneously. It is concluded that nimesulide is as active and safe as paracetamol in treating hyperpyrexia of the aged.