We conducted a case-control study of medulloblastoma/primitive neuroectodermal tumors of brain (PNET) to pursue findings related to vitamin and mineral supplements, micronutrients, and cured meat consumption during gestation. Mothers of 315 cases ages <6 years at diagnosis in 1991 to 1997 identified from the United States and Canada through the Children's Oncology Group and mothers of 315 controls selected by random-digit dialing were interviewed. In the periconception period of the index pregnancy, case mothers were less likely than control mothers to report use of multivitamins [adjusted odds ratio (OR), 0.7; 95% confidence interval (95% CI), 0.4-1.0; P = 0.08] and to be in the highest quartile of iron and folate intake from food and supplements combined (adjusted OR for iron, 0.5; 95% CI, 0.3-0.9; P(trend) = 0.008; adjusted OR for folate, 0.5; 95% CI, 0.3-0.9; P(trend) = 0.007). Case and control mothers had similar intakes of cured meats, although case mothers were more likely to have the combination of high cured meat and low vitamin C intake (OR, 1.5; 95% CI, 1.0-2.3; P = 0.08). The results of the study add to the evidence of a protective role for multivitamins, suggest a possible role for micronutrients early in pregnancy, and generally do not support an association between cured meats and medulloblastoma/PNET.