P53 is one of suppresser genes, located on chromosome 17 P13. Its variant mutant P53 suppresses the programmed cell death. The role of mutant P53 in acute leukemia is still in controversy. This has triggered us to study mutant P53 protein by ELISA assay. This study was conducted on 33 children with acute leukemia 17 patients with Acute Lymphoblastic Leukemia (ALL) and 16 patients with Acute Myeloid Leukemia (AML) beside 10 sex and age matched children taken as control. In all patients, serum mutant P53 protein was increased significantly before treatment (P<0.001) compared to the control. However, serum mutant P53 protein was increased significantly more in AML patients compared to those with ALL. In acute myeloid leukemia, the mutant P53 protein has been correlated with the known standardized international risk criteria for prognosis. The patients who died early before remission induction, were having the highest mutant P53 protein. This study points out that patients with high mutant P53 protein are among the high risk patients.