In this study, we found that : by morphological study alone we could reach definite diagnosis in 18 cases ( 60 percent ) while with the application of various cytochemical tests beside morphological study, proper diagnosis and classification of type of leukemia could be reached in 24 cases ( 80 percent). So cytochemical markers are very useful and simple methods for identification and classification of acute leukemias. However in our study we conclude that cytochemistry is the best method for diagnosis of granulocytic leukemias while for lymphocytic leukemias , it is limited and need immunophentyping. So immunophenotyping tests are recommended for accurate diagnosis, classification and therapy of lymphoblastic leukemias.