Background: Prenatal supplementation has been inversely associated with childhood, but not with infant, leukaemia. Methods: Mothers of 443 cases of infant leukaemia diagnosed during 1996-2006 and 324 frequency-matched controls completed interviews. Associations were evaluated by unconditional logistic regression. Results : We observed no associations between prenatal vitamin (odds ratio (OR)0.79, 95% confidence interval (CI): 0.44-1.42) or iron supplementation (OR1.07, 95% CI: 0.75-1.52) and infant leukaemia after adjustment for race/ethnicity and income. Similar results were observed for leukaemia subtypes analysed separately.ConclusionThe observed null associations may be attributable to high supplementation rates and/or national fortification programmes.