OBJECTIVES: Providing parenteral amino acids to very-low-birth-weight infants during the first weeks of life is critical for adequate growth and neurodevelopment. However, there is no consensus about what dose is appropriate or when to initiate supplementation. As a result, daily practice varies among neonatal intensive care units. The objective of our study was to determine the effects of early parenteral amino-acid supplementation (within 24 h of birth) versus later initiation and high dose (>3.0 g/kg/day) versus a lower dose on growth and morbidities. METHODS: A systematic review and meta-analysis of publications identified by searching PubMed, EMBASE, and Cochrane databases was conducted. Randomized controlled studies were eligible if information on growth was available. RESULTS: The search identified 14 studies. No differences were observed in growth or morbidity after early or high-dose amino-acid supplementation, but for several outcomes, meta-analysis was not possible due to study heterogeneity. Initiation of amino acids within the first 24 h of life appeared to be safe and well tolerated, and leads more rapidly to a positive nitrogen balance. CONCLUSIONS: Administering a high dose (>3.0 g/kg/day) or an early dose (≤24 h) of parenteral amino acids is safe and well tolerated but does not offer significant benefits on growth. Further large-scale randomized controlled trials in preterm infants are needed to study the effects of early and high-dose amino acids on growth and morbidity more consistently and extensively.