Immunophenotype of peripheral blood lymphocytes was studied in 10 children after the cessation of treatment acute lymphoblastic leukemia and in 3 after non Hodgkin's lymphoma non-B. They all were in complete remission. Peripheral blood lymphocytes cells were analysed by flow cytometric analysis. Estimate surface antigens were estimated: CD3, CD19, CD4, CD8, CD3-16+ 56+. The results were compared with data obtained in children not treated because of neoplastic diseases. Our results showed that the absolute number of lymphocytes T(CD3+), TS (CD8+) and NK cells were significantly increased in the study group.