Background: A hydatid cyst is still a serious health problem in endemic areas. Invasion of the spleen is rare in hydatid disease. In the medical literature, reports about isolated splenic hydatidoses are quite rare. Also there is not a consensus about the way of treatment. Methods: Between 1978 and 2000, in our clinic approximately 900 patients were operated on for an abdominal hydatidosis; 850 of these patients were treated for a hepatic hydatidosis and 14 patients for an isolated splenic hydatidosis. Six (42.8%) of the latter patients were male and 8 (57.1%) were female. The mean age of the patients was 47.14 +/- 4.9 (range 17-72) years. Ten patients (71.4%) presented with a painful mass in the left upper quadrant of the abdomen, and the other 4 patients (28.5%) were asymptomatic and were diagnosed incidentally. Results: All of the patients underwent elective splenectomy. There was no mortality, but complications occurred in 4 (28.5%) patients. The period of hospitalization ranged from 7 to 17 days with a mean of 9.8 days. 1 patient died from an acute myocardial infarction during the 2nd postoperative year, and 1 patient died as a consequence of a traffic accident during the 5th postoperative year. Nine patients, after follow-up periods of between 2 and 14 years, are living free from disease. No recurrence occurred in any of them. In the remaining 3 patients, long-term follow-up could not be maintained. Conclusions: A hydatid cyst must be included in the differential diagnosis of cystic lesions of the spleen. A splenic hydatid cyst should be treated surgically due to the high risk of a rupture, and the ideal procedure in adulthood is standard splenectomy. Copyright (C) 2003 S. Karger AG, Basel.