We investigated the relation between concentrations of maternal zinc and copper and the risk of an infant being born with an orofacial cleft. We did a case-control study using 116 mothers of children with isolated cleft lip with or without cleft palate (cleft group), and 64 mothers of unaffected children (control group). Mothers with a whole blood zinc concentration of 47.1 micromol/L or less had a risk 2.5 times higher of having a child with an orofacial cleft than those with a higher concentration (or level) (95% CI 1.03-6.23; p<0.05). A low zinc concentration combined with a high copper concentration was seen only in the cleft group. This evidence suggests an association between concentrations of maternal zinc and the risk of orofacial clefts in offspring.