Japanese persimmon fruits of the 'Fuyu' cultivar were harvested periodically, starting in June with very young fruit (6.5g), and ending in November with overmature fruit (217g). The time course of respiration rate (CO_2 production), ethylene evolution and ripening behaviour of fruits after harvest was observed at 25℃. 1 . In stage I fruits, the rise of respiration (climacteric-like rise), ethylene evolution and flesh softening were initiated together, and the respiration rate and ethylene evolution rose to a maximum and fell off thereafter. There was a close parallelism between respiration and ethylene evolution. The abscission of calyx from fruit was observed around the peak of respiration and ethylene evolution. In stage II fruits, there was no peak in respiration, but a clear peak was observed in ethylene production. There was no abscission of calyx in this stage. In stage III fruits, there was no peak in respiration and ethylene evolution, and the abscission of calyx was not observed. It appeared that the ability of endogenous ethylene synthesis in fruits decreased with their development. 2. The treatment with 10 ppm exogenous ethylene increased the rate of respiration and promoted the initiation of ethylene production and softening of fruits. The effectiveness of ethylene treated seemed to be larger on stage I fruits than stage II and stage III ones. 3. In the case of repeated 1 day treatment of stage III fruits with 10 ppm ethylene, the first treatment could not induce the autonomous ethylene synthesis in fruit, and the second could do. It was thought that the effectiveness of ethylene on fruits had relations with their maturity at harvest.