In order to study the mechanism of the effect of heparin on apoptosis in carcinoma cells, the nasopha- ryngeal carcinoma cell line CNE2 was used to identify the effect of heparin on apoptosis associated with the expression of c-myc,bax, bcl-2 proteins by use of Hoechst 33258 staining, terminal deoxynucleotidyl transferasemediated dUTP nick-end labeling (TUNEL), agarose gel electrophoresis, and flow cytometry, as well as Western blot analysis. The results showed that heparin induced apoptosis of cNE2 cens including the morphologic changes such as reduction in the volume, and the nuclear chromatin condensation, as well as the “ladder pattern” revealed by agarose gel electrophoresis of DNA in a concentration-dependent manner. The number of TUNEL-positive cells was dramatically increased to 33.6+1.2% from 2.8+0.3% by treat- ment with heparin in different concentrations (10~40 kU/L). The apoptotic index was increased to 32.5% from 3.5% by detecting SubG1 peaks on flow cytometry. Western blot analysis showed that levels of bcl-2, bax and c-myc were significantly overexpressed by treatment with the increase of heparin concentrations. These results suggest that heparin induces apoptosis of CNE2 cells, which may be regulated by differential expression of apoptosis-related genes. In order to study the mechanism of the effect of heparin on apoptosis in carcinoma cells, the nasophary ryngeal carcinoma cell line CNE2 was used to identify the effect of heparin on apoptosis associated with the expression of c-myc,bax, bcl-2 proteins The use of Hoechst 33258 staining, terminal deoxynucleotidyl transferasemediated dUTP nick-end labeling (TUNEL), agarose gel electrophoresis, and flow cytometry, as well as Western blot analysis. The results showed that heparin induced apoptosis of cNE2 cens including the morphologic changes such as The reduction in the volume, and the nuclear chromatin condensation, as well as the “ladder pattern” revealed by agarose gel electrophoresis of DNA in a concentration-dependent manner. The number of TUNEL-positive cells was extremely increased to 33.6+1.2% From 2.8+0.3% by treat- ment with heparin in different concentrations (10~40 kU/L). The apoptotic index was increased to 32.5% from 3.5% by detecting SubG1 peaks on flow cytometry. Western b Lot analysis indicated that levels of bcl-2, bax and c-myc were significantly overexpressed by treatment with the increased of heparin concentrations. these rates suggest that heparin induces apoptosis of CNE2 cells, which may be regulated by differential expression of apoptosis-related genes .