OBJECTIVE Cell proliferation and differentiation are directed by cell cycle mechanism. When tumor cells proliferate abnormally, cyclins, which are positive agents of cell cycle, may be expressed abnormally at the same time. Now many references proved that cyclins are highly expressed in solid tumors. This study was designed to investigate the relationship between expression of cyclins and prognosis of acute leukemia. METHODS Sixty-eight cases of acute leukemia were enrolled. Reverse transcription polymerase chain reaction (RT-PCR) was performed on tumor samples to examine the expression of cyclin A, cyclin D, cyclin E. All samples were divided into three groups: acute leukemia in complete remission (12 cases), newly diagnosed acute leukemia (16 cases) and refractory leukemia (40 case). Samples of benign hemopoietic patients were used as normal control (15 cases). RESULTS All the 15 cases in the control group were negative of cyclin mRNA. No difference of cyclin A mRNA expression was shown between control group and the three experiment groups (P >0.05). But expression of cyclin D and cyclin E mRNA was significantly different between them (P< 0.01). There was no difference of expression of cyclin D and cyclin E mRNA among CR patients with acute leukemia(P >0.05), while the expression of cyclin D mRNA is significantly higher than that of cyclin E in refractory leukemia group. Furthermore the expression of cyclin D mRNA in recurrent refractory leukemia patients is significantly higher than that newly diagnosed cases (P< 0.05). All cyclins mRNA positive cases were divided into single cyclin gene expressed group and multiple cyclins gene expressed group. The positive rates of them were counted. No difference was found between complete remission group and refractory leukemia group (P >0.05). CONCLUSIONS Cyclin D may act as a prognostic marker for acute leukemia. The amount of cyclins expressed cannot be used as a prognostic factor for acute leukemia.