OBJECTIVE - To document the incidence of IDDM in Mauritian children and adolescents 0-19 yr of age from 1986 to 1990. RESEARCH DESIGN AND METHODS - We used a population-based register that used pediatricians, physicians, nutritionists, and general practitioners as a primary source of restrospective case ascertainment. The denominator data were obtained from the Statistics Office of the Ministry of Health (Port Louis, Mauritius). RESULTS - In 1990, 37 newly diagnosed IDDM cases (22 females and 15 males) were identified between 1986 and 1990 among the population ≤19 yr of age. The average incidence density per year was 1.9/100,000 people and was slightly higher among girls (2.2/100,000) than among boys (1.5/100,000). The average age-standardized incidence density was 2.1/100,000 people (95% confidence interval 1.5-3.0) among children ≤14 yr of age, 2.5/100,000 people (95% confidence interval 1.5-3.9) among girls, and 1.8/100,000 people (95% confidence interval 1.0-3.0) among boys. The incidence was similarly low in Mauritians of Asian Indian, Chinese, and Creole (predominantly African) origin. CONCLUSIONS - The incidence of IDDM in Mauritian children and adolescents is among the lowest yet reported. This sharply contrasts with the very high risk of NIDDM found among the adult population in this rapidly modernizing country.