Apoptosis is the primary mechanism through which most chemotherapeutic agents induce tumor cell death. The purpose of this study was to monitor the expression of pro- and anti-apoptotic proteins CD(95) , Bcl-2, as well as copper and zinc levels in the peripheral blood of children with acute lymphocytic leukemia (ALL) prior to and 6 months after the beginning of chemotherapy. Blood parameters and bone marrow blast count were also assessed. Twenty of 26 patients who received treatment showed amelioration in apoptotic response, which is reflected in the elevation of CD(95) , whereas Bcl-2 protein was significantly lowered. In these patients, the elevated serum copper level was not significantly affected whereas the low serum zinc level was significantly raised. Improvement in blood parameters and bone marrow blast count were also achieved. Taken together, the data suggested that assessment of apoptosis signaling molecules might have a predictive impact on treatment outcome.