BACKGROUND: Oxidative stress involved in cryopreservation protocols may be responsible for the poor survival of tissues after cryopreservation.OBJECTIVE: In the current study, we aimed to clarify the role of oxidative stress and its relationship with survival rate during cryopreservation of PLBs from nobile-type Dendrobium.MATERIALS AND METHODS: ROS, antioxidants and oxidative products and the survival rate in PLBs from Dendrobium Hamanal Lake Dream were determined during vitrification.RESULTS: Relative survival of PLBs decreased significantly after preculture and rewarming (P<0.01). Generation of ·O2- and protein carbonyl (PCO) increased significantly after preculture. Dramatic increases in ·O2-, H2O2 and MDA, and significant decreases in AsA content, activities of SOD and CAT were observed after rewarming.CONCLUSION: ROS-induced oxidative stress was associated with the poor survival of PLBs following vitrification. ·O2- was the predominant ROS resulting in the decreased survival after preculture, while H2O2 together with ·O2- appear to be responsible for the survival decrease after rewarming.