This study determined the influence of prematurity on the manifestation and treatment of neonatal abstinence syndrome (NAS).This was a medical record review of Australian infants exposed to opiates in 2004 and 2007. Finnegan scores were obtained for 215 of 361 (59%) preterm infants under 37-week gestation and 694 of 1178 (59%) term infants.The mean and standard deviation (SD) gestational ages were 34 (3) and 38 (3) weeks for preterm and term infants, respectively. Maternal daily methadone doses were similar for the preterm and term infants with a mean (SD) of 79 mg (39) versus 72 mg (38) (p = 0.06). Maximum Finnegan scores were significantly lower in preterm infants (10 versus 11, p = 0.01), scores were positively correlated with gestation and fewer preterm infants were medicated for NAS (40% versus 48% p = 0.05). Maximum median daily and interquartile range morphine doses were lower for preterm than term infants (0.5 mg/kg/day (0.3-0.6) versus 0.5 mg/kg/day (0.4-0.7), p = 0.02).Preterm infants were just as likely to be monitored for withdrawal as term infants, but their Finnegan scores were lower and fewer preterm infants were treated for NAS. Whether this indicates decreased NAS severity or physiological immaturity is uncertain. Other means of evaluating NAS in preterm infants are warranted, especially long-term outcomes.