In order to select a population at risk for the development of diabetes for a prospective study of the relationship of islet cell antibodies (ICA), islet cell surface antibodies ( ICSA ), and glucose tolerance after mumps infection, we carried out a screening program for diabetes. A diabetic survey was conducted among 1581 children (less than 16 yr of age) with mumps infection 14 mo before the survey, using a brief questionnaire combined with urinary glucose analysis. Responses to the screening program were obtained from 68.4% (N = 1080) of the children. Out of a total of 1080 subjects, 1069 (99%) had no diabetes mellitus, diabetic symptoms, or glucosuria. A "positive urine glucose screen" was obtained in 11 subjects (1%) of the study group. These individuals all had a normal oral glucose tolerance test according to the new WHO definition. A group of 86 children was randomly selected from the total group of 1080 children for follow-up glucose tolerance, ICA, and ICSA . Irrespective of the negative urine glucose screen impaired glucose tolerance was diagnosed in 3.5% (N = 3) of the 86 children. The prevalence of ICA and ICSA was 78% and 36%, respectively. The simultaneous prevalence of ICA and ICSA was 33%. The pathogenetic role of mumps infection and ICA/ ICSA and their possible relationship to slow progressive beta cell destruction remain to be elucidated.