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