We present the case of an immunocompetent 50-year-old Japanese man with a cerebrospinal fluid (CSF) abnormality relevant to syphilis; his original presentation was liver dysfunction, the etiology of which was uncertain until positive serology for syphilis was identified. Liver dysfunction was promptly resolved after oral penicillin therapy; however, serological recurrence developed. CSF abnormality associated with syphilis was confirmed by subsequent lumbar puncture. Syphilis should be included in the differential diagnosis of patients with liver dysfunction of unknown etiology, and possible neurosyphilis should be considered when the treatment becomes refractory, even when there is no evidence of neurological manifestations.