Studies were conducted on harvesting indices, physico- biochemical changes, respiration and ethylene production (EP), and modified atmosphere storage of mangosteen fruit. The time taken by the fruit of color stages (CS) -1 and 0 to attain ripeness (CS 5) at 25 degree C were 14 and 7 days respectively. Each stage of CS 0-4 had the best eating quality while that of CS-1 had inferior flavor. The respiration pattern of mangosteen fruit resembled that of climacteric fruit with respiration rate increasing from 10 to 30 ml. kg.(-1), and EP rising from 2 to 15 ul.kg.(-1). The peak of EP occurred 2.5-3 days after the climacteric peak (CP). Water applied through cut surface of the fruit stem caused the increases of respiration and EP, and the fruit became CS 4 faster by 2 days. Ethylene application resulted in rapid occurrence of CP, which would be faster with higher concentration of applied ethylene. As a result, it triggered autocatalytic ethylene production. The increases of respiration and EP could be induced by 6-24 hours after dropping the fruit onto the floor. Mangosteen with fruit stem and calyxes dipped in 1,000 ppm GA(,3) solution and whole fruit coated with 10% Sta-fresh # 7055 emulsion had lower concentrations of internal CO(,2) and ethylene as compared to the control during the first 15 days in storage at 13 degree C. After another 15 days under the same storage condition, external apperance and quality of the GA(,3) - treated fruit were marketable.