Parameters of fetal growth in triplet gestations are poorly studied and controversial. A cross-sectional analysis of triplet birth weight was performed to elucidate fetal growth patterns. Birth weight and gestational age data were analyzed on 580 infants in 196 triplet sets (eight stillborn infants excluded) between 1985 and 1988. Ovulation induction was used in approximately one half the gestations and early obstetric and ultrasonographic dating was available in all pregnancies. The mean triplet set and individual triplet weights versus gestational age were calculated with distinctly linear growth displayed between 22 to 38 weeks' gestation. Mean intratriplet differences at all gestational ages were determined. A comparison of singleton and triplet growth curves was constructed to show the distinct growth characteristics of triplets.