The changes in the enzyme activities of sucrose metabolism and physiological changes were investigated in mango fruit cv. Irwin at five development stages [50, 70, 90, 110, 130 days after anthesis (DAA)]. Changes in the respiration rate and ethylene production were higher at 50 DAA than other growth stages and the lowest at 90 DAA. Sucrose accumulation was related to the reduction of sucrose phosphate synthase (SPS; EC 2.4.1.14) activity, whereas acid invertase (AI; EC 3.2.1.26), neutral invertase (NI; EC 3.2.1.26) and sucrose synthase (SS; EC 2.4.1.13) activities were decreased. Moreover, the AI activity is the dominant enzyme that plays a major role in sugar accumulation and quality of mango fruit. Therefore, mango fruit cv. Irwin should be harvested after physiological maturity at 110 DAA.