Oil content and fatty acid composition are the most significant quality criteria of peanuts (Arachis hypogaea L.), and these parameters is greatly influenced by irrigation and fertilization practices. A study was conducted to investigate the effects of irrigation intervals and irrigation levels on oil content and fatty acid composition of peanuts, under sandy soil conditions in two consecutive years, using 'Halisbey', 'NC-7', and 'Sultan' peanut cultivars, commonly grown in Turkey. Irrigation levels were arranged based on total evaporation from Class-A pan, and irrigations were applied through drip lines. Irrigation intervals were set as two and four days, and irrigation levels were set as 50% (I-50), 75% (I-75), 100% (I-100) and 125% (I-125) of Class-A pan evaporations. Oil content, unsaturated fatty acids (oleic and linoleic acids), and saturated fatty acids (palmitic, myristic, arachidic, behenic and lignoceric acids) were determined. For oil content, treatments were identified as the most appropriate irrigation for a two-day irrigation interval of all cultivars, I-100 for four-day irrigation interval of 'Halisbey' and 'Sultan' cultivars and I-75 for four-day irrigation interval of 'NC-7' cultivar. Oleic, linoleic, and palmitic acids were the major fatty acids of peanuts. Cultivars exhibited different variations in these fatty acids based on irrigation intervals and irrigation levels. In general, oleic acid contents decreased, but linoleic and palmitic acid contents increased with increasing irrigation levels. The greatest oleic acid contents were obtained from two and four-day irrigation intervals of I-50 treatments in 'Halisbey' and 'NC-7' cultivars and from two and four-day irrigation intervals of I-75 treatments of the second year in 'Sultan' cultivar. Present findings revealed that for quality peanut production, both irrigation intervals and irrigation levels should be taken into consideration.