To evaluate the expression of cyclin G2 mRNA in patients with acute leukaemia (AL) and its clinical value, the expression of cyclin G2, G1 and P53 mRNA in the bone marrow from 74 AL patients and 10 normal individuals as control were detected with reverse transcription polymerase chain reaction (RT-PCR). The positive segment of cyclin G2 was analyzed by DNA sequencing. The results showed that (1) the positive rate and the expressing level of cyclin G2 in AL patients (52.7%, 0.552 +/- 0.498) were significantly lower than those in normal control (100%, 1.953 +/- 0.675) (P < 0.01); (2) among new diagnosed AL patients, the complete remission (CR) rate (69.2%) in the positive cyclin G2 patients was higher than that (40%) in negative cyclin G2 patients (P < 0.05); (3) the positive rate of cyclin G2 (43.6%) in resistance group was significantly higher than that (68.6%) in sensitive group (P < 0.01); (4) following-up for 14.3 month (11 - 18.5 month) in 28 AL patients with CR, there were 10 relapsed in 11 AL patients with low expression level of cyclin G2 (90.9%); and 7 relapsed in 17 AL patients with high expression (41.2%), and there was significant difference (P < 0.05). In conclusion, the expression of cyclin G2 in AL patients was higher than that in normal control, the abnormal expression of cyclin G2 might be a prognostic marker of CR in AL patients.