Abstract: From the results of the present experiment, it was found that ripening of tomato fruits can be hastened significantly with ethreleither by preharvest spray onto the plants or by dipping the fruits after harvest. Concentrations of the ethrel used for dipping ranged from 1,000 to 4,000 ppm. Temperature higher than 25 ℃ during the ripening period was required in accelerating the fruit colour development, but no consistent differences was found between that of 20 ℃ and that of 30℃ of the dipping solutions used. Preharvest spraying with ethrel (500–2000 ppm) in the field also accelerated the fruit ripening by 6–8 days. The early yield of red mature fruits of the treated lots was thus increased considerably over that of the untreated lots. But it was net the case in the total yield. Such a pattern of yield increase was mainly due to the increase of fruit number per unit area, and not the average weight of fruits. No appreciable change was found in total soluble solids contents in the course of ripening, whereas the titratable acidity decreased rapidly. Maturation of watermelon could also be hastened by spraying with ethrel in the field from 100 to 500 ppm, and harvest was advanced by 5–7 days. Soluble solids contents were found to be higher in all regions of the treated fruits in comparision with the untreated ones at the same calender age of fruit development.