Twenty two years old woman was admitted to the Tokyo Medical College Hospital, complaining of sense of fullness in the left hypochondrium. Physical examination revealed a first-sized tumor without tenderness below the left costal margin. By laparoscopical examination, a part of the cystic tumor between the left lobe of the liver and the enlarged spleen was seen. Based upon the findings of selective angiography of the splanchinic artery and scintigram of the liver and spleen, the tumor seemed to be cyst of the spleen. Splenectomy including cyst was performed and cyst with a single cavity arising from the splenic portal was recognized, in which about 1000ml fluid with dark brown hue was contained. Tumor was size of 23×17×13cm and weighed 1380gr. Histologically, epidermoid cyst was confirmed. This patient had no early history of any disease or any trauma in the abdominal organs. Therefore, it might be impossible to clarify the cause of cystic change. In the light of up to now reported cases of splenic cyst, this case stands No. 17 in cases of epidermoid cyst of the spleen in Japan. This patient is now in good health.