We report a case of young immunocompetent woman who was presented with a left parieto-temporal mass as the first and single manifestation of syphilis. A 23 year-old woman with no significant past medical history was reffered to our hospital due to 3 month history of headache. She had a single unprotected sexual intercourse with a promiscuous man 6 month before the time of admission. Physical and neurological examinations revealed no obvious abnormalities. A brain tumor was firstly suggested according to the findings of brain magnetic resonance imaging (MRI). However, the serologic and cerebrospinal fluid test of syphilis proved to be positive, syphilitic gumma was most likely suspected. She responded dramatically to benzylpenicillin potassium. Cerebral syphilitic gumma is a rare manifestations of the neurosyphilis. Treponemal invasion of the cerebrospinal fluid occurs in approximately 25 to 60% of patients after the infection, but most cases spend asymptomatic. Cerebral gumma should be considered in differential diagnosis of any intracranial mass lesions, even in the early syphilitic stages.