Accurate classification of acute leukaemias is essential for proper case management. The utility of monoclonal antibodies in the diagnosis and classification of acute leukaemias is well established. This diagnostic utility relates primarily to two poiuts : firstly the distiuction between acute myeloid leukaemia and acute lymphoblastic leukaemia and secondly to subtypes of acute lymphoblastic leukaemia. Leukaemic cells were immunophenotyped using the. alkaline phosphatase antialkaline phosphatase techniques. The monoclonal antibodies were .very useful in distinguishing cases of acute myeloid leukaemia from acute lymphoblastic leukaemia. Cases of acute lymphoblastic leukaemia with CDI0 positivity showed a better prognosis. T-cell acute lymphoblastic leukaemia was uncommon and was associated with unfavourable prognosis. The alkaline phosphatase antialkaline phosphatase technique served as a reliable and convenient method for immunophenotyping of Ieukaemias, MJAFI 1995; 51 : 165-169