The clinical course of syphilis may be altered in some patients with human immunodeficiency virus type 1 infection. We report two cases of syphilis in patients with human immunodeficiency virus type 1 infection who presented with marked unilateral anterior cervical adenopathy after engaging in oral-genital sex. Neither of the patients had evidence of oropharyngeal chancres. one patient developed a cutaneous rash of secondary syphilis soon after the cervical adenopathy developed. Both patients responded well to antibiotic therapy.