This study was aimed to explore fgfr3 gene expression in leukemic cells and its clinical significance. The expression levels of fgfr3 mRNA in 4 leukemic cell lines and bone marrow samples from 96 patients with leukemia and 14 controls were assayed by RT-PCR. 96 patients with leukemia included 36 cases of acute myeloid leukemia (AML), 29 cases of acute lymphoblastic leukemia (ALL), 31 cases of chronic myelogenous leukemia (CML). The results indicated that fgfr3 gene could be detected in both K562 and U937 cell lines, but not in HL-60 and SHI-1 cell lines. The positive expression rates of fgfr3 mRNA in AL and CML were 46.15% and 51.61% respectively, and were higher than that in control (14.29%, p < 0.05). The positive expression rates of fgfr3 mRNA in AML and ALL were 44.44% and 48.28% respectively, and were higher than that in control (p < 0.05). The increased level of fgfr3 mRNA had a positive correlation with high white blood cell count of > or = 20 x 10(9)/L (p < 0.05). Higher fgfr3 mRNA expression positively correlated with fuse genes of bcr/abl in ALL (r = 0.151, p < 0.05). The expression of fgfr3 gene in AL was not related with chromosome abnormality. In conclusion, the over expression of fgfr3 gene exists in AL and CML patients, it suggests that fgfr3 gene may be partially involved in leukemogenesis.