Objective We studied associations between the type of feeding in infancy and the incidence of insulin-dependent diabetes mellitus (IDDM). Research Design And Methods We studied 103 newly diagnosed diabetic children Results The risk of IDDM was decreased (P < 0.05) among children breast-fed for at least 7 mo (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.24–0.85) or exclusively breast-fed for at least 3 (OR 0.33, 95% CI 0.13–0.84) or 4 (OR 0.43, 95% CI 0.22–0.84) mo. Also, children who were ≥4 mo old at the time of introduction of supplementary milk feeding had a lower risk of diabetes (OR 0.48, 95% CI 0.26–0.91). Conclusions The protective effects of a long duration of breast-feeding and a late introduction of dairy products on the risk of IDDM remained significant after adjusting for the mother's education.