OBJECTIVE: To compare age-standardized incidence rates of diabetes in children 0-14 yr of age and cows' milk consumption in various countries. RESEARCH DESIGN AND METHODS: Ecological correlation study. Only incidence rates from diabetes registries carefully validated by the Diabetes Epidemiology Research International Study Group were used-Finland, Sweden, Norway, Great Britain, Denmark, United States, New Zealand, Netherlands, Canada, France, Israel, and Japan. Data on fluid cows' milk consumption in corresponding countries were obtained from the International Dairy Federation. RESULTS: Correlation between milk consumption and incidence of insulin-dependent diabetes mellitus (IDDM) was 0.96. The data fit a linear regression model, and analysis showed that 94% of the geographic variation in incidence might be explained by differences in milk consumption. CONCLUSIONS: The results support the hypothesis that cows' milk may contain a triggering factor for the development of IDDM.