Objective: To determine Toxoplasma gondii (T. gondii) as a cause of morbidity and mortality in human immunodeficiency virus (HIV) infected patients by ELISA method and to investigate toxoplasmosis-associated risk factors. Methods: This cross sectional study was conducted with 385 patients with HIV/AIDS referred to the behavior disease consultation center in Kermanshah, Iran between May 2012 and June 2013. Anti-Toxoplasma IgG and IgM antibodies were measured by using the ELISA method. Also, the relationship between the infection and age, gender, education, occupation, antiretroviral status, CD4+ cell counts and some other factors of the patients were assessed. P<0.05 was considered statistically significant. Results: Among the HIV-positive patients, 40.8% (157/358) and 2.6% (10/358) patients were positive for anti-T. gondii IgG and IgM antibodies, respectively. The mean CD4+ count in the patients with HIV was 327 cells/µL. A significant correlation was observed between the toxoplasmosis infections with the age group (P<0.05). Nevertheless, no statistically significant difference was found between gender, living area, educational level, occupational, marital status, antiretroviral status, prophylaxis, CD4+ cell count and toxoplasmosis. Conclusions: This study revealed that the patients with HIV infection were at the high risk of developing toxoplasmosis disease especially those patients who do not receive antiretroviral therapy and prophylaxis. The development and use of the effectiveness-based guidelines for controlling and the prevention reactivation of the latent T. gondii infection is required.