An association between zinc depletion and intrauterine growth retardation might occur through disturbed prostaglandin (PG) synthesis. The zinc content and PG metabolism of leucocytes from control, nonpregnant women and mothers 24–48 h after delivery, were measured and related to fetal growth and maternal smoking. Mothers of small for gestational age babies had lower polymorphonuclear and mononuclear cell zinc contents than mothers of appropriate for gestational age babies or nonpregnant controls. Monocytes were the major leucocytes producing PGs. Mothers of small for gestational age babies had higher PGE2:F2aratios than mothers of appropriate for gestational age babies. PGF2aproduction and PGE2a:F2aratio were correlated with tissue zinc status. Monocytes from nonsmokers tended to produce more PGs than those from smokers but the differences were not significant. Mild maternal zinc depletion is not significantly sufficient to alter absolute PG production, but is associated with altered differential production of PGs in human leucocytes. Zinc depletion or malnutrition may contribute to intrauterine growth retardation by affecting placental and/or umbilical PG production.