The possible relation between child's early diet and risk of childhood leukemia has remained largely unexplored. The authors' objective was to determine what particular foods consumed early in life (first 2 years) are associated with risk of childhood leukemia in a 1995-2002 case-control study of a diverse California population. Dietary data were obtained from a questionnaire administered to the child's caregiver. Conditional logistic regression was used to analyze 328 case-control sets matched on age, sex, Hispanic status, and maternal race. Regular consumption of oranges/bananas (odds ratio = 0.49, 95% confidence interval: 0.26, 0.94) and orange juice (odds ratio = 0.54, 95% confidence interval: 0.31, 0.94) during the first 2 years of life was associated with a reduction in risk of childhood leukemia diagnosed between the ages of 2 and 14 years. Restricting the analysis to leukemia diagnosed between the ages of 2 and 5 years reflected a similar pattern of reduced risk. No association between eating hot dogs/lunch meats and risk of leukemia was found. These results suggest that fruits or fruit juices that contain vitamin C and/or potassium may reduce the risk of childhood leukemia, especially if they are consumed on a regular basis during the first 2 years of life.