Abstract: Heavy metals can occur the large-scale cell death of tobacco suspension cultures.TUNEL study and genomic DNA gel electrophoresis showed that this kind of cell death was accompanied by PCD-specific DNA ladder.This result supports that cell death caused by Cd is a kind of programmed cell death(PCD).We have also found that the oxidative and the malondialdehyde(MDA)levels of the stressed cells were enhanced in PCD process,this phenomenon shows that the reactive oxygen species(ROS)in the stressed cell was increased.This suggests that the PCD of tobacco cells are tightly linked to the ROS.