Abstract: Objective To explore the expression of FUS-CHOP mRNA and MDM2、p53 protein in Myxiod/round cell Liposarcoma and their significance. Methods Twenty-five formalin-fixed, paraffin-embedded MRCL samples and 18 control cases retrieved from the archival files were studied. Nested reverse transcription-polymeras-ase chain reaction(RT-PCR)technique was employed to detect the FUS-CHOP mRNA expression, followed by DNA sequencing to confirm the PCR product. β-actin gene was used to assess the quality of the mRNA templates.All of the MRCL cases was available for immunohistochemical analysis of MDM2 and p53 status. Results 　β-actin mRNA was detected in 18 MRCLs (18/ 25, 72 %) and 12 negative cont rol case (12/ 18, 66. 7 %) . Type Ⅱ FUS-CHOP mRNA was successfully detected in 15 out of 25 (60 %) MRCLs. All of cont rol cases were negative for the FUS-CHOP fusion gene t ranscript s. The positive rate of MDM2 and p53 proteins were 56 %(14/ 25) and 44 %(11/ 25), respectively. both of them were significantly higher in round cell liposarcoma than them in myxiod and mixed liposarcoma, There was no correlation between FUS-CHOP mRNA and the expression of p53 、MDM2 protein, but there was a tendency of positive correlation between the expression of MDM2 and p53. Conclusion 　(1) FUS-CHOP is considered as a specific molecular and genetic hallmark for MRCLs and is useful for the diagnosis of MRCLs. (2) The expression of MDM2 and p53 protein is associated with the progression of MRCLs. (3) There is a no correlation between MDM2 、p53 and FUS-CHOP in MRCLs.