Mesenteric and omental cysts are infrequently encountered, benign, intraabdominal tumors. Nineteen new patients were analysed. The most common presenting symptoms were abdominal distension (74%) and abdominal pain (63%). A palpable abdominal mass was found in 58 percent of cases. A correct preoperative diagnosis was established in 91 percent of the patients who were examined by abdominal ultrasonography. Of 19 cases documented at laparotomy, 14 patients (74%) had mesenteric, and five patients (26%) omental cysts. Eleven of the former were located in the small bowel mesentery. All of the cysts were completely removed, and in eight of them bowel resection was required. Subtotal gastrectomy was performed in one case. The mortality rate was 0%. After a mean follow-up period of five years, no recurrence was observed. Our study showed that abdominal ultrasonography by experienced professionals is the most reliable diagnostic tool for detecting these lesions.