Mesenteric cysts are rare abdominal findings. Due to absent or unspecific clinical presentation, very low incidence, and lack of adequate classification these cysts may sometimes represent a diagnostic and therapeutic challenge. We report a case of 37-year-old man with vague palpatory tenderness in left hypochondrium and paraumbilically and with palpable large intra-abdominal mass in whom mesenteric cyst was diagnosed using US and CT imaging. He was operated and cyst was extirpated in toto. Histopathological examination revealed a thick fibrous cyst wall with the signs of chronic inflammation and without inner epithelial lining, which suggested its traumatic origin. Considering the possibility of malignancy mesenteric cysts should be radically resected (with resection of adjacent organs if necessary) due to their strong relapsing potential and a tendency for sudden, progressive local enlargement if not removed in toto.