Abstract The human T-cell lymphotropic virus-1 (HTLV-1) affects worldwide population; the estimated number of currently infected individuals is 10-20 million. In this report, we describe the clinical findings of three family members with vertical transmission of HTLV-1. This case report highlights the importance of healthcare providers who have optimal knowledge about HTLV-1 including its transmission and pertinent attributes, and who are able to provide affected individuals with adequate information regarding their condition.