OBJECTIVE Minimally invasive procedures in small infants and neonates are being performed in increasing numbers. In this study, we describe our institution's experience with laparoscopic Nissen fundoplications (LNFs) in children weighing less than 5 kg. METHODS All cases of LNF attempted in children weighing less than 5 kg since January 2003 at a tertiary-care pediatric hospital were reviewed after Institutional Review Board approval. RESULTS One hundred twenty-two children weighing less than 5 kg underwent LNF during the study period. They ranged from 2 weeks to 3 years of age (mean, 94 +/- 61.3 days) and weighed 1.94 to 4.99 kg (mean, 3.68 +/- 0.77 kg). Twenty-nine percent (n = 35) were neurologically impaired. Eighty-eight percent (n = 107) had concurrent gastrostomy tube placement. Eight (7%) were converted to laparotomy. The average operative time was 112 +/- 46 minutes. Seventy-one percent (n = 87) required intensive care unit use for an average of 14.3 +/- 17.4 days. The average time to start enteral feeds was 2.6 +/- 2.6 days. Thirty-one percent (n = 38) required postoperative mechanical ventilation for an average of 12.0 +/- 20.6 days. The average hospital length of stay was 36.6 +/- 36.0 days (range, 3-175 days). Six patients (5%) had a complication or recurrent gastroesophageal reflux. Three patients had recurrent reflux, one of which underwent another LNF. One patient had a gastric perforation. Another required a redo LNF after a disrupted wrap was noted at a recurrent hiatal hernia repair. Lastly, one patient had bleeding from an accessory hepatic artery with liver retractor placement. CONCLUSIONS Laparoscopic Nissen fundoplication can safely and effectively be performed in small children (<5 kg) with similar outcomes and rates of complication as previously published reports in larger children. These children, however, do have prolonged intensive care unit and mechanical ventilation use associated with their prematurity and significant comorbidities.