Corticosteroid usage was assessed in rheumatoid arthritis (RA) and psoriatic arthritis (PA) patients in Italy. A multicentre, observational study was undertaken in 10 Italian rheumatological centres from 1990 to 1992 using a computerised clinical data bank. Nine hundred and seven RA patients and 180 PA patients were studied; 510 (56.2%) RA patients and 44 (24.4%) PA patients were using corticosteroids. The percentage of patients taking corticosteroids ranged from 20.5 to 85.4% for RA patients and from 0 to 55% for PA patients for the different centres. Methylprednisolone was the most prescribed corticosteroid, both in RA patients (63.2%) and in PA patients (65.9%). The average methylprednisolone daily dose was 5.7+/-3.6 mg in RA patients and 4.5+/-1.4 mg in PA patients. The data provide evidence that corticosteroids are taken in an unexpectedly high percentage of patients with RA and PA in Italy.