On those maternity wards where "rooming in" is not practiced, infants are fed according to fixed schedules. The purpose of this study was to investigate possible differences between two common feeding regimens, three-hourly vs. four-hourly feeds during the first 3 days of life. A group of 152 singleton, full-term infants with birth weights 2,500-2,990 g, born at Bikur Cholim Hospital in Jerusalem from February 1988, to August 1988, were randomly assigned to one of two breast-feeding groups and followed prospectively. The study group (62 infants) was breast-fed every 4 hours, and the control group (90 infants) every 3 hours. The two groups were statistically similar for mean maternal age, parity, ethnic origin, social class, neonatal Apgar scores, birth percentile, and mean birth weights. Infants who breast-fed every 4 hours did not have greater transitional weight loss or higher serum bilirubin levels compared to infants fed at 3 hour intervals.