The purpose of this prospective study was to determine the incidence of visualization of the fetal gallbladder, to characterize its shape, to determine its normal measurements, and to correlate its size with gestational age. Data were collected between January and April of 1993 from the ultrasound laboratories of three major hospitals in the greater New York City area.Fetuses with any anomalies were excluded from the study. Gestational age as determined by ultrasound ranged from 15 weeks to term. Experienced sonographers at each site and the investigator followed a scanning protocol requiring the identification of the fetal gallbladder by shape, measurement in two axes, and evaluation of its content. Measurements of fetal gallbladder length and width were correlated with the estimated ultrasound gestational age. Fetal position and the number of hours since the mothers last meal were also noted. The fetal gallbladder was observed in 84% of the examinations. The most common shape was the teardrop configuration (58%). Fetal gallbladder length and fetal gallbladder width correlated significantly with gestational age as estimated by ultrasound (r = 0.85 and ~.74, respectively; P = 0.05). Echogenic material was noted in one (1.7%) of the fetal gallbladders. The percentage of fetal gallbladder visualization was higher than in previous reports. Even though a significant correlation was found between size and gestational age, more quantitative studies with a larger sample would be needed for development of a fetal gallbladder nomogram.