Prevalence of diabetes mellitus in Japan was investigated through studying the published reports from 1964 to 1992 by searching the electronic data base and some leading Japanese journals following certain inclusion criteria. Out of total 74 retrieved reports, 14 were found eligible for review, some containing data of multiple community and / or periods and were converted into total of 40 reports following a predetermined criteria. Review analysis of only the prevalence of diabetes was done paying much attention to age range, survey methodology and response rate. Oral glucose tolerance test (OGTT) was done in 19 (47.5%) with and in 21 (52.5%) reports without initial urine and / or blood sugar screening. OGTT was done using 75, 50, or 100 grams glucose following either Japan Diabetes Society or WHO criteria. The recent prevalence was estimated ranging from 9.6-11.9% in both sexes of 40 years or over, 4.2-13.1 % in men and 2.6-12.9% in women. The higher prevalences were found in and around 1990 and the lower values in and around 1970. Regression analysis shows the upward trend of the prevalence of diabetes 2.2% in men (p<0.01), 1.6% in women (p< 0.01) by 10 years. J Epidemiol, 1999 ; 9 : 155-162