Background: We report an unusual complication after Lap-Band ® placement characterized by herniation of the anterior stomach through the band. Methods: Group 1 - 105 patients: Operated elsewhere (prior to US FDA approval) and followed by us; perigastric technique was used in 74 and pars flaccida in 31. Group 2 - 218 patients: Operated by us since August 2001 using the pars flaccida approach only. 4 patients with this unusual problem were identified. Results: Patients were all female, with age 37.5 (3343) yr, weight 143.7 (123-167) kg, and BMI 54 (45-65). Onset occurred at 9 (5-16) months, with weight loss: 38.5 (27-53) kg and %EWL 47.3 (31-54)%. All had sudden nausea, vomiting and epigastric abdominal pain that persisted despite emptying the band. None of these symptoms were related to a recent band adjustment. CT scan showed a paragastric Richter's hernia of the stomach underneath the band. At exploration, the band was in the normal location. 3 patients from Group 2 had Richter's hernia of the anterior stomach through the band; reduction of the stomach with closure of the defect was performed. One patient from group 1 had gangrene of the entrapped stomach, resulting in band removal and gastrectomy. Conclusion: Lap-Band^® patients with sudden nausea, vomiting and abdominal pain, when not relieved by emptying the band, should undergo a CT scan. If a traditional slippage is not confirmed, paragastric Richter's hernia of the stomach through the band should be suspected. Immediate exploration with reduction of the stomach and closure of the defect can salvage the stomach and the band. Gastro-gastric sutures must completely close the space underneath the band to prevent this complication.