Background Preterm infants are scheduled to receive total feeding amount in either 3-hour or 2-hour intervals. A gavage feeding may be required if the scheduled amount is not completed orally. Feedings every 2 hours are one-third smaller than feedings every 3 hours. Thus, if the volume of each feed is reduced by decreasing the feeding interval from 3 to 2 hours, the likelihood that the infant completes each volume orally increases, and the probability of requiring gavage feeding decreases. The impact of feeding with 2-hour or 3-hour intervals on time to achieve full oral feeding in preterm infants was investigated. Methods Infants on full enteral gavage feedings were randomized into 2 groups to receive feedings in either 3-hour or 2-hour intervals. The time to achieve full oral feeding and the duration of feeding transition from gavage to oral feedings were investigated. Data were presented as median (interquartile range). Results The study included 100 infants (gestational age: 29 [28-31] weeks, birth weight: 1205 [1040-1380] g) with 50 in each group. The postmenstrual age to achieve full oral feeding was 35 (35-37) weeks in the 3-hour-interval group and 35 (34-36) weeks in the 2-hour-interval group; P = 0.131. The duration of feeding transition was similar between groups. Conclusions Feeding every 2 hours caused no improvement in the time to achieve full oral feeding. The 3-hour-interval feeding is appropriate for the neonatal units, where less handling of preterms and decreased workload of nurses are valuable.