Male pseudohermaphrodites is one of abnormalities of phenotypic sex and have an XY chromosome constitution and testes, but the internal or external genitalia are to some degree those of a female. We surveyed one case which were referred in Veterinary Medical Teaching Hospital of Seoul National University. When patient was purchased, its phenotype was entirely female that have female external genitalia. However, from the age of 6 months, clitoris was gradually increased to Os clitoris, and patients showed male behavior. Critical clinical sign was trauma of protruded Os clitoris. In radiographic and ultrasonographic examination, he had normal vagina and urinary bladder. In chromosome examination, he had an XY chromosome constitution. This case was performed removal of Os clitoris and ovariohysterectomy.