This interventional study was done to determine the effect of parenteral amino acid supplementation on weight change, biochemical effect and incidence of sepsis in preterm low birth weight newborns during their hospital stay. It was carried out during the period of June 2006-May 2007 in the Newborn unit of a tertiary care hospital of Bangladesh. Sixty preterm (28-34weeks), low birth weight (1000-1800g) AGA (appropriate for gestational age) newborns were enrolled within 24 hours of birth. Intervention and control newborns were matched in terms of birth weight and gestational age. Samples were volunteers. Parenteral amino acid (5%) supplementation in addition to usual nutritional management until enteral feeding reached three fourth of total calorie intake. Usual nutritional management was 10% intravenous dextrose and subsequent enteral feeding. Main outcome measured with weight change, biochemical effect and incidence of sepsis. Weight change was observed by two parameters such as mean percentage of maximum postnatal weight loss and mean days to reach birth weight, both were significantly lower in intervention than control group (p<0.05). Biochemical effect of parenteral amino acid supplementation investigated in this study has been shown to have no effect. There was no difference in incidence of sepsis between intervention and control group (p>0.05). Improved nutritional supplementation with parenteral amino acids resulted in better growth as evident by lesser degree of weight loss and earlier regaining of birth weight in the early neonatal period. Biochemical parameters are not affected by parenteral amino acid supplementation.