Abstract: A comparative study on cytogenetics between 30 persons aged more than 95 years and 30 adults were performed. The difference between the longaeval and the controls were significant for rate of chromatid aberration （2.30 VS 1.56％, P＜0.05）, sister chromarid exchange （SCE） frequencies （5.3±1.5 VS 4.1±0.6 per cell, P＜0.05） and hypodiploid （8.88 VS 6.78％, P＜0.05）. But the average mitosis index was found ot be 6.85 VS 6.56％ （P＞0.05）. So it is believed that their increase may be an indication of ageing, and that the cells in longaeval persons can keep up the ability of exuberant division. There was no significant difference between two groups in micronucleus frequencies obtained with the cytochalasin B method （15.2 VS13.9‰, P＞0.05）.