The changes in fat concentration and cumulative fat losses that occur during the delivery of human milk using two different continuous infusion systems were compared with the changes in fat concentration during simulated intermittent gavage or bolus feedings. With both mechanical pumps the largest cumulative fat losses and the greatest decreases in fat concentrations occurred at the slowest infusion rates. State of homogenization of the milk generally made little difference in the changes in fat concentration using the syringe pump, whereas homogenizing the milk increased the fat concentration significantly with the roller pump. With the syringe pump the positioning of the syringe tip (horizontal or vertical) made no difference in fat concentration at an infusion rate of 1 ml/hr, whereas at 4 and 7 ml/hr the fat concentration was increased significantly by keeping the syringe tip vertical. With either mechanical pump a large fat bolus was delivered during the eighth and final hour of infusion if the milk remaining in the tubing was recovered by using air infusion at the same infusion rate. Intermittent bolus delivery of human milk resulted in no significant loss of human milk fat, no changes in fat concentration, and no terminal delivery of a large fat load. Thus intermittent bolus feedings are preferred over continuous mechanical pump infusion systems for the delivery of human milk to low-birth-weight infants.