Chloroporphyrin derivative (CPD1) 20mg ? L-1 plus light 5min caused marked photohemolyses, At the dose of 10mg ? L-1 20mg ? L-1 plus light10min. the activities of AchEs in red cell membane and ATPase in liver mitochondria and G-6-Plus in liver microsome were markedly inhibited lipid peroxida- tion of red cell membrane was greatly enhanced by CPD1 plus light when CPD1 was irrad - iated the production of free radical of superoxide anion was initiated the amount of O2 production was depen-dent on CPD1 doses and irradiation time.