Mesenteric panniculitis is a very rare disease usually involving the mesentery of the small bowel, less frequently the sigmoid colon or other intraabdominal fat tissue. The disease is benign with a favorable prognosis. Diagnosis is, as a rule, established at operation or autopsy and histology. A 58 year old male with this disease is presented. The paticut hod mild abdominal pain and a palpable mass. A tumor of the mesentery was suspected on CT scan. The exact diagnosis was established at operation and confirmed at histology.