This paper reports a case of Petersen's space hernia after mini gastric bypass. This is an anecdotal post-operative complication in the mini gastric bypass technique, with an estimated rate of 1/5000 cases. Similar cases described in the literature were treated by the surgical hernia reduction and the closure of the mesenteric defect. Our patient had a unique management, performing a conversion to Roux-en-Y gastric bypass with dissection of the biliopancreatic limb at the anastomosis and creation of a variable foot-point anastomosis with excellent mid-term post-operative results. This should provide better long-term results as compared to simple mesenteric closure, avoiding the complications of mini gastric bypass technique.