AIM: To study the changes of mitochondrial membrane potential(△ψm) and mitochondrial mass in apoptosis of Jurkat cells induced by camptothecin(CPT).METHODS: Jurkat cells were treated with CPT.Annexin V-FITC/propidium iodine(PI) double stainig was used to detected early stage of apoptosis and PI staining for analyzing the cell cycle.Jurkat cells were stained by annexin V-PE/DiOC_6(3) to detect changes of △ψm.The mitochondrial mass was measured by cytometry with NAO staining.RESULTS: 6 h after treated with 10 μmol/L CPT,the rate of early apoptotic cells(22.59±1.04)% had significantly difference compared with control group(3.93±0.73)%(P<0.01).The necrotic rate(2.48±0.53)% had no significant difference to that in control group(2.78±0.63)%(P>0.05).Apoptotic peak appeared obviously after treated with CPT,the percentage of late apoptotic cells(13.58±0.97)% had distinctly difference compared with control group(3.18±0.51)%(P<0.01).The cells in G_0/G_1 phase(48.14±0.96)% were much higher than that in control group(44.09±0.43)%(P<0.01).Mitochondrial depolarization was very obviously in CPT group.The percentage of annexin V~+DiOC_6(3)~-cells was(19.47±0.69)%,while in control group,was(4.21±0.40)%(P<0.01).Mitochondrial mass in CPT group was significantly lower than that in control group,the percentage of NAO~+ cells(74.77±1.66) % had significantly difference compared with control group(92.24±1.41)%(P<0.01).CONCLUSION: During the process of CPT-induced apoptosis in Jurkat cells,mitochondrial depolarization was very obviously and mitochondrial mass decreased,indicating that the process of apoptosis is nearly related to the mitochondrial pathway.