Background: Toxoplasmosis, a worldwide parasitic infection, is considered as a transfusion-transmitted disease. Objectives: Due to ignorance about Toxoplasma infection in blood donors monitoring and its important role in provision of safe blood and blood products and also poor information about the seroprevalence of T. gondii infection in blood donors, this study was conducted to assess anti-Toxoplasma gondii antibodies and associated risk factors among blood donors in northwest of Iran.