OBJECTIVE: To study the association between parent carbohydrate counting knowledge and glycemic control in youth with type 1 diabetes. RESEARCH DESIGN AND METHODS: We assessed 67 youth ages 4-12 years with type 1 diabetes (duration >or=1 year). Parents estimated carbohydrate content of children's meals in diet recalls. Ratios of parent estimates to computer analysis defined carbohydrate counting knowledge; the mean and SD of these ratios defined accuracy and precision, respectively. A1C defined glycemic control. RESULTS: Greater accuracy and precision were associated with lower A1C in bivariate analyses (P < 0.05). In a multivariate analysis (R(2)= 0.25, P = 0.007) adjusting for child age, sex, and type 1 diabetes duration, precision (P = 0.02) and more frequent blood glucose monitoring (P = 0.04), but not accuracy (P = 0.9), were associated with lower A1C. A1C was 0.8% lower (95% CI -0.1 to -1.4) among youth whose parents demonstrated precision. CONCLUSIONS: Precision with carbohydrate counting and increased blood glucose monitoring were associated with lower A1C in children with type 1 diabetes.