To compare the results of fluorescence in situ hybridization (FISH) versus conventional cytogenetics (CC) in the detection of common chromosomal abnormalities and evaluate the significance of FISH in myelodysplastic syndrome (MDS) .A total of 344 patients with de novo MDS from June 2008 to October 2012 were detected by 6 pairs of probes, including CSF1R/D5S23-D5S721 (5q33) , EGR1/ D5S23-D5S721 (5q31) , D7S486 (7q31) /CSP7, D7S522 (7q31) /CSP7, D20S108/CSP8 (20q12/CSP8) and CSPX/CSPY