Human T-cell lymphotropic virus type 1 (HTLV-1) can cause adult T-cell leukaemia/lymphoma (ATLL). Two patients originating from the Caribbean area with ATLL are described. The first patient developed respiratory insufficiency due to acute T-cell leukaemia. The diagnosis was suspected because of characteristics of abnormal lymphocytes in the blood smear. The second patient had lymphadenopathy and developed severe hypercalcaemia. Both patients were typical cases of ATLL. The pathogenesis, clinical manifestations, pitfalls and treatment of this intriguing disease are discussed.