OBJECTIVE: Small bowel series (SBS) may be a useful test in identifying the causes of feeding intolerance in preterm infants. Unfortunately, little is known about the safety and effectiveness of SBS in preterm infants. By scrutinizing our recent experiences in performing SBS in preterm infants, we aim to provide basic data concerning the use of SBS in preterm infants with feeding intolerance. METHODS: Between January 2005 and October 2008, SBS was done in 46 preterm infants with feeding intolerance, who were admitted to the neonatal intensive care unit (NICU) of Seoul national university children's hospital. We conducted a retrospective analysis of these preterm infants. RESULTS: The average gestational age and birth weight of the 46 infants were, 30(+1)+/-3(+5) weeks, 1,435+/-623 g, respectively. The mean postconceptional age when SBS was done, was 37(+2)+/-4(+2) weeks, 46.8+/-27.3days. SBS proved that 29 infants did not have mechanical obstructions and 22 of these infants had delayed bowel transit time. Eventually, 35 infants attained full feeding except those who underwent operation. SBS was done at their bedside in 15 out of 27 infants in the group less than 1.5 kg. History of NEC, meconium related ileus, and gastrointestinal operation were more frequent in the group less than 1.5 kg. The adverse effects of SBS in preterm infants included vomiting, delayed transit of the contrast media, all of which resolved in the end and there were no reports of aspiration or sepsis. CONCLUSION: Actively performing SBS test in preterm infants with feeding intolerance will promote feeding advancement by discovering the cause of feeding intolerance and subsequent management of the specific problem.