The aim of this study was to estimate the number of patients treated for chronic pancreatitis in 1993 in Japan and to explore the clinico-epidemiological features of chronic pancreatitis. Two surveys were conducted. Stratified random sampling was used to select departments in which patients with chronic pancreatitis were treated, and two different questionnaires were administered to obtain relevant information. From the first survey, the total number of patients treated for chronic pancreatitis in Japan in the year 1994 was estimated as 32 000 (95 % confidence interval, 25 000-39 000). Clinico-epidemiological features, based on the 2523 patients reported from the second survey, were subsequently clarified. The sex ratio (male/ female) of the patients was 3.5. Alcoholic pancreatitis was the most common type in males (68.5%), and idiopathic pancreatitis in females (69.6%). Compared with the findings in the last survey in 1985, the proportion of patients with alcoholic pancreatitis has decreased slightly from 58.7% to 55.5%, while that of idiopathic chronic pancreatitis has increased in both males and females. Patients diagnosed by advanced techniques such as computed tomography (CT) and endoscopic retrograde cholangiopancreatography (ERCP) accounted for 68.1% of the total. The number of patients with chronic pancreatitis treated in 1994 in Japan, was estimated as 32 000, with an overall prevalence rate of 45.4 per 100 000 population in males and 12.4 per 100 000 population in females.