Abstract Background The incidence of internal herniation (IH) post Roux-en-Y gastric bypass (RYGB) is variable across literature (0.5–11%). This may be partially related to the difference in the operative techniques of RYGB. Routine closure of mesenteric and Petersen's defects has shown noticeable decline in the incidence of IH over last few years. Nevertheless, it didn't prevent the development of IH at long-term follow up. Methods We describe a video of a case with a large non-obstructing mesenteric internal hernia post RYGB. A 33 years old female patient presented to our bariatric clinic with recurrent attacks of post-prandial abdominal pain over 6 months. She had RYGB 2.5 years before this presentation, with EWL of 65%. Of note, the mesenteric and Petersen's defects were closed in the original RYGB operation. CT scan showed suspicious findings of internal herniation without obstructing signs. Patient had a laparoscopic exploration which showed a large internal herniation through mesenteric defect containing more than two thirds of bowel length. Closure of the defect was done by a purse string technique using non-absorbable prolene 2/0 stitch after reduction of the bowel. Patient had an uneventful postoperative recovery. She denied any further attacks of abdominal pain at her follow up till 6 months postoperatively. Conclusions Diagnosis of non-obstructing internal herniation post RYGB is very challenging. Low threshold for laparoscopic exploration in suspicious cases of remittent abdominal pain is highly recommended. CT scan can't rule out IH completely due to its intermittent nature. Laparoscopic repair remains the optimal approach, even in the large IH, with favourable outcomes. Appropriate identification of the bowel configuration is the key step in such procedure.