Adult T-cell leukemia/lymphoma (ATLL) is an aggressive neoplasm of the T-cells caused by the infection with human T-cell lymphotropic virus type-1 (HTLV-1). ATLL is classified into four subtypes, namely acute, lymphoma, chronic, and smoldering. The acute, lymphoma and chronic unfavorable types are considered aggressive forms of ATLL. We present some peripheral blood smear images of a patient diagnosed with acute type ATLL.