Mesenteric cysts are rare abdominal tumors. They are found in the mesentery of small bowel in 66% and mesentery of large intestine in 33%, usually in the right colon. Very few cases have been reported of tumors found in mesentery of descending colon, sigmoid or rectum. We are presenting a case of a 48 year old lady, who presented with severe left sided abdominal pain for 1 day, with no previous history of trauma or surgeries. Examination revealed a tender mass in the left hypochondrium. CT scan findings showed 7 x 4 x 3 cm cystic lesion most likely to be mesenteric cyst arising from the mesentery of the splenic flexure of the colon infected or leaked into the surrounding mesentery and peritoneum producing congestion and inflammatory process. Laparoscopic excision of the cyst undertaken, patient recovered well and discharged the following day. Histopathology showed Cystic mass in which the wall comprises fibrous tissue, adipose tissue and inflamed granulation tissue. There are small necrotic areas, hemorrhagic areas and aggregates of neutrophils. No epithelial lining is identified. There is no evidence of malignancy in the sections examined. This is one of the rare cases of mesenteric pseudocysts of the large bowel.