Cystic lymphangioma (CL) is a benign rare malformation of lymphatic vessels. Its discovery in adults is rare. Although it can affect any organ, the common forms found in adults are mesenteric and/or retroperitoneal CL. This article was designed to study the epidemiological, diagnostic difficulties, and therapeutic principles of intra-abdominal cystic lymphangioma in adults. We report a retrospective study from January 1998 to September 2010 concerning 20 patients who underwent surgical removal of a CL. We were interested in discovering the clinical, biological, and radiological characteristics of CL. The localization, size, and number of cysts have been reported, as well as the surgical intervention used and the postoperative immediate and late complications. The median age was 46 years. Abdominal pain was the main symptom and was found in 15 patients (75%). Physical examination revealed an abdominal mass in 12 patients (60%). In four patients (20%), the cystic lymphangioma was incidental. Abdominal ultrasound and abdominal CT scan helped to highlight 22 cystic masses. CL diagnosis was established preoperatively in 13 patients (65%). Six patients (30%) were operated with a diagnosis other than CL. The diagnosis was made intraoperatively in one case (5%). Only two patients (10%) were operated on in emergency: one due to an infected CL and the other was CL complicated with intracystic hemorrhage. A laparotomy in 13 cases (65%) was the surgical approach used, whereas 7 cases (35%) benefited from a laparoscopy. No conversion was noted. The majority of the patients, 18 cases (90%), received a total cystectomy. Only two patients (10%) had recurrences of which only one was reoperated. The diagnosis of CL often is facilitated by means of modern imaging; however, other diagnoses may be discussed, particularly hydatid disease endemic areas. If symptomatic lesions or complications arise, complete surgical excision, when possible without major sacrifice, seems to be the best therapeutic option to reduce the risk of recurrence.