Over a period of 3-1/2 years, 86 cases of acute leukemia were analyzed by immunohistochemical (IHC) means on ficoll separated cytospin preparations of peripheral blood and/or bone marrow samples. Antibodies included in the panel were specific against Tdt, HLA-DR, CD19/CD20/CD22, CALLA (CD10), CD2, CD11C as well as against Ig heavy chains. Of 86 cases analyzed, 48 cases were of ALL, (25 of common pre-B ALL, 15 of pre-B/NULL and 8 of T ALL phenotype), twenty-four (24) out of 86 cases were of non-lymphoblastic (AML/AMML) type. In six cases, there was suggestion of a mixed lineage, while in 8 cases there was inconclusive diagnosis. Mean age was lower in common ALL sub-set of ALL as compared to pre-B/NULL group (i.e., 8 vs 12 years), while in non-lymphoblastic group it was 36 years. T cell phenotype was invariably seen in young adults, who usually presented with a mediastinal mass.