Background: Laparoscopic surgery in small infants is still an uncommon procedure in Japan. The present study was conducted to evaluate the advantages and disadvantages of laparoscopic surgery in neonates and infants weighing less than 5 kg. Methods: Between July 1997 and November 1999, 54 infants underwent laparoscopic surgery. They were evaluated for length of operation, intra- and postoperative complications, changes in intra-operative body temperature, time to postoperative feeding, length of hospital stay and changes in serum levels of C-reactive protein (CRP), creatinine phosphokinase (CPK) and interleukin (IL)-6 on days 0, 1 and 4. These parameters in the laparoscopic pyloromyotomy (LP) and laparoscopic fundoplication groups were compared with those in the open pyloromyotomy (OP) and open fundoplication groups, respectively, which were performed during the same period. Results: Three laparoscopy cases were converted to open procedures. One case of fundoplication had panperitonitis due to failed gastrostomy and required long-term parenteral nutrition. Time to postoperative feeding and length of hospital stay in the LP group were significantly shorter than in the OP group. In LP group, intra-operative body temperature did not markedly decrease during CO: pneumoperitoneum. Although serum levels of CRP, CPK and IL-6 were elevated in all groups on postoperative day 1, there were no significant differences between the groups. Conclusions: Better quality of life after laparoscopy is a significant advantage over conventional surgical procedures. This advantage not only outweighs the incidence of intra- and postoperative complications in small infants, but further emphasizes the need to improve laparoscopic techniques to avoid complications.