Syphilis is a sexually transmitted disease with varied and often subtle clinical manifestations. Primary syphilis typically presents as a solitary, painless chancre, whereas secondary syphilis can have a wide variety of symptoms, especially fever, lymphadenopathy, rash, and genital or perineal condyloma latum. In latent syphilis, all clinical manifestations subside, and infection is apparent only on serologic testing. Late or tertiary syphilis can manifest years after infection as gummatous disease, cardiovascular disease, or central nervous system involvement. Neurosyphilis can develop in any stage of syphilis. The diagnosis of syphilis may involve dark-field microscopy of skin lesions but most often requires screening with a nontreponemal test and confirmation with a treponemal-specific test. Parenterally administered penicillin G is considered first-line therapy for all stages of syphilis. Alternative regimens for nonpregnant patients with no evidence of central nervous system involvement include doxycycline, tetracycline, ceftriaxone, and azithromycin. In pregnant women and patients with neurosyphilis, penicillin remains the only effective treatment option; if these patients are allergic to penicillin, desensitization is required before treatment is initiated. Once the diagnosis of syphilis is confirmed, quantitative nontreponemal test titers should be obtained. These titers should decline fourfold within six months after treatment of primary or secondary syphilis and within 12 to 24 months after treatment of latent or late syphilis. Serial cerebrospinal fluid examinations are necessary to ensure adequate treatment of neurosyphilis.