Background: Little is known about how maternal zinc intake influences growth in utero and in postnatal life in humans. Objective: We aimed to assess the effect of maternal zinc supplementation during pregnancy on infant growth through age 1 y. Design: A double-blind, randomized controlled trial of prenatal zinc supplementation was conducted from 1995 to 1997 in Lima, Peru. Women (n = 1295) were enrolled at 15.6 ± 4.6 wk gestation and assigned to receive daily supplements with zinc (15 mg Zn + 60 mg Fe + 250 μg folic acid) or without zinc (60 Fe + 250 μg folic acid) through pregnancy to 1 mo after delivery. At birth, 546 infants were followed for 12 mo to assess growth. Anthropometric measures of body size and composition were collected monthly, and morbidity and dietary intake surveillance was carried out weekly. Results: No differences in maternal socioeconomic characteristics by treatment group or follow-up period were found. Infants born to mothers prenatally supplemented with zinc had significantly (P < 0.05) larger average growth measures beginning in month 4 and continuing through month 12. In longitudinal regression modeling, prenatal zinc was associated with greater weight (by 0.58 ± 0.12 kg; P < 0.001), calf circumference (by 1.01 ± 0.21 cm; P < 0.001), chest circumference (by 0.60 ± 0.20 cm; P = 0.002), and calf muscle area (by 35.78 ± 14.75 mm2; P = 0.01) after adjustment for a range of covariates. No effect was observed for linear growth. Conclusion: Maternal zinc supplementation in this population was associated with offspring growth, which is suggestive of lean tissue mass accretion. © 2008 American Society for Nutrition.