The care of neonates treated in neonatal intensive care units (NICUs) is a complex undertaking, making the use of medications a challenge. Prescribers must take care in assessing the impact of various medications on neonate health. This module examines the impact of weight, body composition, genetics and other factors in neonatal medication use. It also discusses the use of specific medications in neonates, the determinants of neonate drug responses, and various challenges in neonatal clinical pharmacology, including drug absorption and other issues.