The micronucleus frequency (MNF) in peripheral blood lymphocytes (PBL) is a biomarker of chromosomaldamage and genome instability in human populations.The relationship of micronucleus frequency with prognosisof patients with acute leukemia is not clear. We therefore investigated MNF in mitogen-activated peripheralblood lymphocytes from patients with hematologic diseases and solid tumours. Patients included 50 with acuteleukemia, 49 diagnosed with myelodysplastic syndrome (MDS), 54 with benign blood diseases, and 45 with solidtumours, examined with 50 healthy controls. The mean MNF was significantly higher in cases of hematologicdiseases and solid tumor patients than in healthy controls (P<0.001). There was no evident difference betweenMNF in the acute leukemia (7.15±2.18) and solid tumor groups (7.11±1.47), but both were higher than in the MDSgroup (5.12±1.29) and benign blood diseases group (3.08±1.08). Taking 7.15‰, the average MNF of the acuteleukemia group as standard, and dividing 50 cases of acute leukemia patients into high MNF group (MNF≥7.15‰)and low MNF group (MNF<7.15‰). The overall response (complete remission + partial remission) rates of thelow MNF group were significantly higher than in the high MNF group (P=0.001). The high MNF group furthershowed lower overall survival rates than the low MNF group. MNF expression and progression-free survivalseemed to have a opposite relationship, with a correlation coefficient of -0.702. These data indicate that MNFin peripheral blood lymphocytes is important for evaluation of prognosis of acute leukemia patients, and it canreflect progression of disease to a certain degree.