Abstract: The deep research of relation of apoptosis with radiotherapy makes it necessary to be clear about the relationship between apoptosis and radiosensitivity,so that this will provide a new standard of forecast and evaluation for clinical radiotherapy.These days study indicates that apoptosis and radiosensitivity have a subtle and complex relationship.This article reviews as follows regarding the relation of apoptosis rate ,cell cycle position and radiation dose rate with radiosensitivity.