Abstract: Objective：To investigate the different effects of adenovirus-expressed E1A gene (Ad-E1A) on human laryngocarcinoma cell Hep-2, human melanoma cell A375 and human hepatocarcinoma cell SMMC-7721 in vitro, and to select the differential sensitivity of these cell lines to Ad-E1A. Methods ：RT-PCR was applied to examine the transcription of E1A gene in the infected carcinoma cells.Cell growth inhibition was detected by MTT assay.Hochest staining was applied to the observation of morphological changes of nucleus.Apoptosis and cell cycle were tested by flow cytometry. Results ：E1A gene is expressed in all these carcinoma cells, which significantly inhibited cell growth.In 72 hs the growth inhibiting rate of Ad-E1A on Hep-2， A375, SMMC-7721 cells are 18.65 %, 33.02% and 36.32% respectively,and the counterparts are 29.95 %， 45.36% and 54.11% in 96 hs.Among the three cell lines SMMC-7721 cell demonstrated the highest sensitivity to E1A which also induced apoptosis of SMMC-7721 cells at a rate of 36.92%.Hoechst staining finds that Ad-E1A can induce apoptosis of human carcinoma cell as shown by classical karyopycnosis, ruptured apoptotic body and morphological changes of the nuclei. Conclusion ：Ad-E1A inhibits the growth of these three carcinoma cells， among which SMMC-7721 cell is the most sensitive and A375 cells the second and Hep-2 cells the least. Furthermore Ad-E1A can also induce apoptosis of these carcinoma cells significantly.