Changes in the activities of the cell wall degrading enzymes pectinesterase (PE), polygalacturonase (PG) and cellulase were studied during the ripening of fruit from ‘Kitch- ner’, ‘Dr Knight’ and ‘Abu-Samaka’ mango cultivars. PE activity decreased continuously during ripening of ‘Kitchner’ and ‘Dr Knight’, while that of ‘Abu-Samaka’ increased up to firmness 88 N, and subsequently decreased. Activities of PG and cellulase increased progressively during the ripening of fruit of the three cultivars with a high correlation between the increase in the activity of the two enzymes and the loss of fruit firmness. A key role of PE in controlling fruit softening rate in mango was identified.