ABSTRACT: Olives belong to the family of olea europaea L. is a popular fruit tree. The fruit and the oil extracted from it is consumed worldwide particularly in the Mediterranean regions. In this study changes in the fatty acid composition of the oil extracted from olive fruit during the course of maturation is investigated. This work is concerned with the best harvesting point when oleic acid the predominant fatty acid reaches its maximum concentration. Three different varieties of olives from Fars province were chosen and subjected to oil extraction. The quantitative and qualitative determinations concerned with the fatty acids were carried out on the oil and concluded that maturation of olives depending on the variety played an important role in the fatty acid composition of the extracted oils.