Because leukemia clone-specific chromosomal abnormalities are present at birth in children who later develop leukemia, it has been hypothesized that maternal factors, including nutrition during pregnancy, might affect the risk of acute lymphoblastic leukemia (ALL) among young children. We have evaluated this hypothesis in a nationwide case-control study of ALL among children ages 12 to 59 months in Greece. Children (n=131) with ALL were gender and age matched to control children (n=131) hospitalized for minor conditions between 1999 and 2003. The mothers of the children were interviewed in person by trained interviewers who used an extensive food frequency questionnaire addressing diet during the index pregnancy. The analysis was done by modeling the data through conditional logistic regression, also controlling for total energy intake and possible confounding factors. Odds ratios (OR) and 95% confidence intervals (95% CI) were expressed per quintile increase of maternal intake during pregnancy of the specified food group. The risk of ALL in the offspring was lower with increased maternal intake of fruits (OR, 0.72; 95% CI, 0.57-0.91), vegetables (OR, 0.76; 95% CI, 0.60-0.95), and fish and seafood (OR, 0.72; 95% CI, 0.59-0.89) and higher with increased maternal intake of sugars and syrups (OR, 1.32; 95% CI, 1.05-1.67) and meat and meat products (OR, 1.25; 95% CI, 1.00-1.57). Children of women who tend to consume during their pregnancies what is currently considered to be a healthy diet maybe at lower risk of ALL.