The prevalence of diabetes in Minnesota school-age children was found to be one per 529 students (1.89 per 1,000), 95 per cent of whom were receiving insulin. Data were obtained by a mail survey of the public schools in the state. Enrollment in public schools represents 90 per cent of the student population in Minnesota, and data were received from 96 per cent of the public schools. This return rate by schools accounts for 95 per cent of the total student enrollment. Diabetes increased linearly with age, representing a yearly prevalence increase of 0.16 cases per 1,000 students.