Human T cell lymphotropic virus (HTLV) I/II is a retrovirus that is usually transmitted through transfusion of cellular blood products, sexual contact, and vertically from mother to child through breastfeeding. Policies to screen donated blood for this virus have varied from country to country, based on seroepidemiological data. Before 1991, no such data existed on HTLV-I/II among the Saudi population. Since then, several reports have documented a low seroprevalence rate among Saudi blood donors (0-0.026%). We did a retrospective review of all blood donated at King Fahad National Guard Hospital over the preceding 3 years to assess the seroprevalence of HTLV-I/II. After retesting positive and borderline samples, we were able to detect 1 positive and 38 borderline samples. As well, we reviewed the Saudi literature to identify the national seroprevalence of the disease and propose a cost-effective approach for screening donated blood in Saudi Arabia for HTLV-I/II.