Subcutaneous and intraperitoneal cysticercosis due to Taenia crassiceps was diagnosed in a 5-yr-old male ring-tailed lemur (Lemur catta) in the Madrid Zoo-Aquarium (Madrid, Spain). Under laparoscopic examination, several septated fibrous cystic structures and numerous masses of small transparent vesicles (ca. 3 mm in diameter) were observed subcutaneously and inside the peritoneal cavity. Most of the structures were extirpated but, after 2 days of postsurgical intensive care, the animal died. The loss of body weight of the animal after surgical extirpation (566 g) represented 22% of the total weight (body weight before mass removal, 2,582 g). The vesicles were identified under light microscopic examination as cysticerci and by molecular diagnosis as Cysticercus longicollis, the larval form of T. crassiceps. The present report represents the first detection of T. crassiceps in the prosimian genus Lemur.