A computer analysis system, automated imaging cytometry (AIC), flow cytometry (FCM) and EM, were used to study the relationship of apoptosis and the change of DNA in mouse HepA cells subjected to hyperthermia. Our results showed that pyknotic rate in the 44 ℃ group was significantly increased (P＜0. 01 ) when compared with that in the 37 ℃ group, both the diploid rate and aneuploid rate in the 44 ℃ group were significantly decreased (P＜ 0. 01 ) when compared with that in the 37 ℃ group. The pyknotic rate determined by ALC was in conformity with the apoptotic index (AI) determined by FCM. Under EM, ultrastructures of HapA ells appeared typical apoptosis changes in the 44 ℃ group. We are led to conclude that (1) when the temperature is 42 ℃ or 44 ℃ for 2 h, it did not promote the necrosis of HepA cells; (2) when the temperature is 42 ℃ for 2 h, it did not obviously induce the apoptosis of HepA cells, and the 44 ℃ for 2 h obviously induced the apoptosis of HepA cells; (3) AIC method can be used as an aid for the measurement of apoptotic index. Further study is needed to established it as a novel, simple and convenient method for determining the apoptosis.