A 31-year-old homosexual man, who was human immunodeficiency virus (HIV)-positive was admitted for fever and cough. Chest computed tomography (CT) revealed the presence of diffuse interstitial reticular nodulation, and brain nuclear magnetic resonance imaging showed the presence of nodular frontal lesions. Microscopic examination of sputum and other body fluids showed the presence of acid-fast bacilli and culture-only growth Mycobacterium tuberculosis. Serology for respiratory tract pathogens was negative except for Chlamydia. An antibody titer in the immunoglobulin G (IgG) class of 1:64 for Chlamydia pneumoniae and, unexpectedly, an antibody titer of 1:1024 for C. trachomatis were found. The patient was successfully treated with antituberculosis agents, and clarithromycin, for presumptive chlamydial infection.