The effects of A L tonic capsule on DNA content in rat experimental hepatocarcinogenesis induced by diethylnitrosamine (DENA) were observed. The experimental rats were divided into 4 groups. With exception of group D in which the rats were only administered with DENA, the rats in the groups A, B, C were previously, simultaneously and subsequently fed with A L tonic capsule respectively while they were administered with DENA. The DNA content of all rat livers was measured using automatic image analysis technique 20 weeks after administration of DENA. The results showed that the highest and lowest DNA contents were respectively seen in the groups D and A. There was significant difference in DNA contents between the groups A or B or C and D, and also between the groups A and B or C (both P <0.01). 4 components (4C) and ≥5C cells were predominant in the group D, while 2C cells were the minority. The number of 2C cells in the groups A, B, C was significantly higher than that in the group D, and the number of ≥5C cells in the groups A, B, C was markedly lower than that in the group D ( P <0.01). Also, there was very significant difference in the number of 2C and ≥5C cells between group A and B or C ( P <0.01). It was concluded that A L tonic capsule could effectively inhibit the increase of DNA content of hepatocytes and improve the distribution of DNA content in rat hepatocarcinogenesis, especially in group A. The effects of AL tonic capsule on DNA content in rat experimental hepatocarcinogenesis induced by diethylnitrosamine (DENA) were observed. The experimental rats were divided into 4 groups. With exception of group D in which the rats were administered only with DENA, the rats in the groups A, B, C were previously, simultaneously and concurrent fed with AL tonic capsule respectively while they were administered with DENA. The DNA content of all rat livers was measured using automatic image analysis technique 20 weeks after administration of DENA. The results showed that that the highest and lowest DNA contents were respectively seen in the groups D and A. There was significant difference in DNA contents between the groups A or B or C and D, and also between the groups A and B or C (both P <0.01) . The number of 2C cells in the groups A, B, C was significantly higher than that in the g roup D, and the number of ≥ 5C cells in the groups A, B, C was markedly lower than that in the group D (P <0.01). Also, there was very significant difference in the number of 2C and ≥5C cells between group A and B or C (P <0.01). It was concluded that AL tonic capsule could effectively inhibit the increase of DNA content of hepatocytes and improve the distribution of DNA content in rat hepatocarcinogenesis, especially in group A.