An experimental investigation was carried out on olive oils of the Ogliarola Salentina and Coratina cultivars to assess the in¯u- ence of the two di€erent olive grinding techniques and kneading process on the quality of the oils. The experimental data obtained showed that resistance to oxidation, total phenols and phenolic compounds analysed for HPLC were higher in the Coratina oils than in the Ogliarola oils. The use of hammer-crushers plus kneader rather than stone mills plus kneader always produced sig- ni®cant increases in the total phenols. Resistance to oxidation was assessed by the Rancimat method and showed a signi®cant correlation with the amounts of total phenols and of an unidenti®ed substance (peak I) which was conspicuously present amongst the substances evaluated for HPLC.