Background: Transfusion transmissible infections (TTIs) are the most frequent complication of blood transfusions. This fact stresses the need for regular evaluation and monitoring of TTIs in blood donors. Objectives: This study was done to determine the prevalence of the hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and syphilis among blood donors at the South Khorasan Transfusion Center (SKBTC) in South Khorasan Province, Iran. This report is the first of its kind that has been performed in this region. Methods: A retrospective study was carried out on 165,267 blood donors at the SKBTC from 2006 to 2016. Data were analyzed on the metrics of donation status, age, gender, educational level, and serologic results for the infectious markers. Statistical analysis was performed using SPSS software (version 16.0). Results: The overall seroprevalence rates of HBV, HCV, and HIV infections per 100,000 donations were 247, 21, and 0.6, respectively. There was no positive donor for syphilis. HBV and HCV infections in first-time donors were present at significantly higher rates than in regular and repeat donors (P < 0.001 and P = 0.003, respectively). Although gender was not found to be significantly associated with HBV and HCV (P = 0.32), there was a significant relationship between younger age (P < 0.001) as well as lower educational level and hepatitis agents (P < 0.001). Moreover, being single evinced a significant association with HCV seropositivity (P = 0.001). Conclusions: This report found a decreased prevalence of TTIs relative to the most of previous reports. This decrease may have resulted from public health programs, improved donor selection, improved recruitment of repeat/regular donors, and the use of highly sensitive kits for the screening procedure.