A hypothalamic hamartoma is a congenital tumor-like neural malformation. It is usually seen in children and is associated with neuroendocrinological symptoms, seizures, or psychological impairments. An asymptomatic hypothalamic hamartoma in an adult is extremely rare. This report describes an asymptomatic adult with a large hypothalamic hamartoma associated with polydactyly in his feet. Both polydactyly and hamartoma are rare lesions; therefore, this may not be a coincidental presentation. It is thought to have occurred in the embryonic period presumably between 37 and 40 gestational days.