The immunosuppressive effect of cytotoxic drugs, basic therapeutic agents in the treatment of childhood acute leukemias, requires monitoring of the immune system following cessation of therapy. The cytokines are soluble proteins that play a key role in the immunoregulation of the lymphocyte function. The cytokines regulate growth, differentiation and function of various cells in normal conditions. The aim of our study was to estimate serum levels of IL‐2, IL‐6, IL‐8, IL‐10 and TNF‐alpha in children with acute lymphoblastic leukemia (ALL) after cessation of chemotherapy. The study involved 150 children with ALL. This group consisted of: 30 children 1 month after treatment cessation; 30 children, 3 months later; 30 children 6 months later; 30 children, 9 months later and 30 children, 12 months later. The control group consisted of 30 healthy children. The levels of the cytokines under study were assayed using the immunoassay kits (R&D Systems, USA). During the study significant differences in TNF‐alpha, IL‐2 and IL‐8 serum concentrations were observed among treated children and controls. However there were no differences in IL‐6 and IL‐10 concentrations. Copyright © 2004 John Wiley & Sons, Ltd.