There are very few postharvest studies about the mamey sapote fruits. The lack of appropriate harvest indexes for this crop result in fruits having a wide variability in maturity after harvest. Fruit skin shows no apparent changes in color as maturity progresses. Another complication results from harvesting the fruit with long poles, which restricts the harvester from touching the fruit to evaluate fruit softening. The objective of this study was to evaluate the effect of exogenous ethylene applications to fruits on increasing the uniformity of fruit maturity. Fruits were harvested every 2 weeks over a 4-month period. Fruit harvest was initiated 8 weeks before the estimated ripening day. Fruits were treated by immersion for 1 min in an ethephon solution at 0, 500, or 1000 mg·liter–1 and stored at 20°C (65% RH) for 4 or 8 days. After the storage period, fruits were analyzed for fruit firmness, color (external and internal), pH, titratable acidity, soluble solids content, ascorbic acid, and starch. Postharvest exogenous applications of ethylene stimulated postharvest ripening of the mamey sapote fruits. Ripening was associated to fruit softening, a change in pulp color from a pale pink to an intense pink color, and an increase in SSC. Fruit response to exogenous ethylene applications was small in immature fruits and increased as fruits approached the ripe stage, and decreased again in over-ripe fruits. In conclusion, postharvest applications of ethylene increased both fruit earliness and maturity uniformity in fruits.