DNA from 36 patients with chronic myelogenous leukemia (CML) at various clinical stages and 6 cases of acute leukemia was investigated for alterations of the p53 gene by Southern blot analysis. Rearrangements of the p53 gene were seen in 3 of 12 (25.00%) cases of blast crisis and accelerated phase (AP) of CML and in only one of 18 chronic phrase (CP), just as has been reported previously. Meanwhile, by restriction fragment length polymorphism (RFLP) analysis the Bgl II site polymorphism in the p53 gene was also found. The frequency in Chinese people detected here was 0.392, which was strikingly higher than that in some other countries (P < 0.001). These results suggested that the alterations of the p53 gene, for example, p53 rearrangements, were probably responsible for the progression of BC in some CML patients, and that the frequency of Bgl II polymorphism in the p53 gene might be related to the population distribution.