Background and Objectives:Human T-cell lymphotropic virus type-I (HTLV-I) infection is considered as a public health challenge in endemic areas. The virus is associated with severe diseases, such as adult T-cell leukemia/lymphoma, and HTLV-I-associated myelopathy/tropical spastic paraparesis. One of the major routes of the HTLV-I transmission includes blood transfusion. Sabzevar is located in the endemic region of HTLV-I infection. The aim of the present study was to determine the seroprevalence of HTLV-I infection in the blood donors in Sabzevar.Materials and Methods:A total of 35,067 blood donors in Sabzevar from March 2009 to April 2012 who were screened with HTLV-I on the enzyme-linked immunosorbent assay screening test were included in this survey. Reactive samples that confirmed by western blot were considered to be seropositive cases. The required data were obtained from blood donors’ database of blood transfusion service.Results:The overall prevalence of HTLV-1 based on the positive result of western blot test was 0.14%. The seropositive donors aged 17–59 years with a mean age of 38.10 ± 11.82. The prevalence rates of HTLV-I infection in 3 years of study were 0.19%, 0.14%, and 0.09%, respectively. A significant relation between age, sex, educational level, and history of blood donation was observed with seropositivity of HTLV-I.Conclusion:The improvement of donor selection and laboratory screening caused a decline in the prevalence of infection in blood donors. Given the lower prevalence of infection in regular donors with lower age and higher educational level, more efforts should be done to attract blood donors from these populations.