The fat content and fatty acid composition of 9 Turkish pistachio varieties grown in Ceylanpinar, Sanliurfa-Turkey and 36 Iranian pistachio varieties and genotypes grown in Iran were investigated. Twenty seeds from each variety were randomly selected and the kernels were analyzed. Oil extraction and fatty acid methyl ester formation were done in a single step and the composition of fatty acids was determined by gas chromatography. Fat content of the Turkish varieties ranged from 48.55% to 58.50% and Iranian varieties ranged from 47.65 to 63.31 %. Palmitic acid, which is the main saturated fatty acid, ranged from 8.27% to 11.07% in Turkish and 8.40% to 10.87% in Iranian varieties. Palmitoleic acid content was less than 1% in Turkish cultivars, and ranged between 0 and 1.46% in Iranian varieties. The stearic acid content of the Turkish pistachio varieties ranged from 0.20% to 2.79% whereas Iranian varieties contained from 0.44% to 1.80% stearic acid. Oleic acid content ranged from 53.16% to 72.63% in Turkish varieties and from 51.80% to 71.23% in Iranian nuts. Linoleic acid content was between 16.58 and 35.40% in Turkish varieties and between 17.36% and 35.16% in Iranian varieties.