In patients with acquired immunodeficiency syndrome (AIDS), toxoplasmosis almost exclusively involves the central nervous system (CNS), and extra-CNS organ infection is rare. We report a case of Toxoplasma gondii colitis in a patient with AIDS characterized by the following: 1) onset of diarrhea was simultaneous with disseminated toxoplasmosis; 2) T. gondii was found in colonic biopsies, whereas other infectious causes of diarrhea had been ruled out; 3) diarrhea was cured by anti-Toxoplasma therapy.