BACKGROUNDThe most common alternatives in feeding preterm infants are bottle feeding and cup feeding. However, there is no clear and precise clinical evidence to show the superiority of a single method. New studies are needed to eliminate confusion on this subject.AIMThe effects of oral feeding methods on the transition to direct-breastfeeding and length of stay in preterm infants.METHODSThis retrospective study was carried out in a single NICU. Data was collected from the digital records and correlated the effects of bottle feeding and cup feeding. One hundred fifty-eight preterm infants (30–34 weeks) met the inclusion criteria. Seventy-eight of them were bottle-fed, and eighty of them were cup-fed.RESULTSStatistical analysis (Mann-Whitney U test and t-test) has shown that there was no statistically significant difference between the two groups (bottle & cup) in terms of transition to direct-breastfeeding and length of hospital stay (p > .05).CONCLUSIONSAs a result of the current study, both feeding methods are equally effective and can be used as alternative oral feeding methods.