Human T-cell Lymphotropic virus type I (HTLV-I), is associated with certain hematological and neurological disorders. Seroprevalence studies demonstrated that the distribution of HTLV-I is heterogeneous worldwide and not specific to one region. While the seroprevalence of HTLV-I/II among blood donors in Lebanon and Saudi Arabia is generally very low, this questioned the need for routine HTLV screening for blood donors. As blood is one of the major routes of transmission of the virus, blood banks of several countries routinely screen all blood donations for HTLV-I. The aim of the present study was to assess the seroprevalence rate of HTLV-I/II antibodies among blood donors in two distinct Arab communities: Lebanon and Saudi Arabia (Eastern Province). Blood samples of 3,529 blood donors were collected at Blood Banks of four major hospitals in Lebanon, together with samples from 13,443 blood donors in Eastern Saudi Arabia, Dammam region. Initial Enzyme Linked I Immunosorbent Assay (ELISA) screening resulted in 23 (0.7%) positive samples, of which 12 (0.3%) were reconfirmed positive by ELISA, of whom only two (0.06%) were confirmed positive by Western Blot analysis of whom only one tested positive for HTLV-I by PCR (0.028%). Similarly, ELISA screening followed by confirmation by Western Blot resulted in 8 (0.060%) positive cases, of which 5 (0.056%) belonged to Saudi and 3 (0.113%) to non-Saudi donors. While it’s very low prevalence among Lebanese and Saudi blood donors does not support routine screening of Lebanese and Saudi blood donors for HTLV-I, screening of blood donors from other nationalities may be exercised, especially those from HTLV-I endemic areas.