OBJECTIVE To investigate whether zinc supplementation during pregnancy improves maternal and fetal outcome. METHODS Controlled clinical trial started at registration until discharge of mother and child from hospital. Two thousand volunteer mothers were randomly assigned to receive zinc supplementation or placebo in a double blind trial. METHODS Women less than 20 weeks pregnant at the first visit who agreed to take part in the study. One thousand two hundred and six mothers were available for study. METHODS Volunteers were randomly selected to receive two tablets of zinc (44 mg zinc in total) or two placebo tablets containing inert substances, indistinguishable in appearance and taste from the zinc tablets. METHODS Large for gestational age (LGA), small for gestational age (SGA), premature rupture of the membrane (PROM), preterm labor (PL), preeclampsia and bleeding in the second or third trimester. RESULTS There were no differences between mothers given zinc supplementation concerning the outcome parameters and those given placebo. CONCLUSIONS Zinc supplementation in pregnancy in a normal healthy middle class population in Denmark does not seem to offer any benefits to the mother or her fetus.