The clinical contribution and cost effectiveness of pharmacist involvement in peripheral-vein total parenteral nutrition (TPN) in a neonatal intensive-care unit was studied. Fourteen neonates who received a standardized TPN solution without pharmacist monitoring (Group 1) were compared with 14 neonates who received an individualized TPN solution with pharmacist monitoring (Group 2). Infants were excluded from the study if they received oral feeding, or TPN for less than five days, or were fluid-restricted. No significant difference in mean gestational age, birth weight, gestational size, age at initiation of therapy, duration of therapy, or daily amount of fluid administered was found between the two groups. The mean weight gain in Group 1 (4.9 g/day) was significantly less than in Group 2 (11.8 g/day) (p less than 0.02). The amount of protein provided to Group 2 (2.2 g/kg/day) was significantly greater than to Group 1 (1.9 g/kg/day) (p less than 0.01). The number of calories provided per day was greater for Group 2 (63 kcal/kg/day) than for Group 1 (53 kcal/kg/day) (p less than 0.001). When only those infants who received lipids were analyzed, Group 2 received significantly more lipid (2.0 g/kg/day) than group 1 (1.5 g/kg/day) (p less than 0.001). The mean daily cost was greater for Group 2; however, when cost was related to efficacy, Group-2 cost per gram of weight gain was lower than Group-1 cost. Pharmacist monitoring of an individualized program of TPN in neonates provided a greater mean daily weight gain, allowed a greater amount of nutrients to be provided, and was cost effective compared with the use of a standardized solution without pharmacist monitoring.