118 patients who had recovered from acute pancreatitis underwent endoscopic retrograde pancreatography (ERCP) during a long-term follow-up (mean 4.4 years, range 1-17) to investigate the frequency and features of residual ductal lesions. Oedematous and necrohaemorrhagic pancreatitis occurred in 35 and in 83 patients, respectively. The aetiology was biliary (39 patients), alcoholic (32), biliary-alcoholic (18) and miscellaneous (29). After oedematous pancreatitis, ERCP was normal in 31, showed obstructive pancreatitis in 2 and a slight localized and smooth stricture of the main duct in 2 patients. After necrotizing pancreatitis, 29 patients showed ductal changes without features of chronic pancreatitis, 7 obstructive, 3 chronic calcifying pancreatitis and 44 normal pictures. In 17 patients submitted to two or three ERCPs during a mean 10-year follow-up, the ductal appearance was unchanged in 12, worsened in 3, and improved in 2 patients. The aetiology of pancreatitis and frequency of recurrences was similar in patients with or without scarring lesions. We conclude that residual ductal lesions are common after acute necrotizing pancreatitis.