Abstract: The total alkaloids of T. glandulosissimum and its main component hernandezine were found to be effective for treatment of mice bearing P388 leukemia, S180 ascites and C26 colon cancer. Although hernandezine inhibited the growth of mouse L1210 cells and human oral cancer KB cells in vitro markedly, its inhibitory effect on normal hemopoietic progenitor cells (CFU-GM) in mice was relatively low. Preliminary results showed that hernandezine blocked cell-cycle transfer from G1 to S phase, and its cytocidal action might be cell cycle specific. In addition, two other components, thalidezine and isothalidezine, isolated from the same plant exerted similar inhibitory effect on L1210 cells.