Oleic and linoleic acid together constitute about 80% of the fatty acid composition in peanut oil. Increasing the ratio of oleic to linoleic acid will improve the keeping quality of peanut oil. A University of Florida breeding line, designated F435, averages 80% oleic acid and 2% linoleic acid. Initial genetic studies of this fatty acid composition showed that a single recessive gene controlled the trait in two genetic backgrounds and a second recessive gene was necessary for expression in a third background. Further studies have shown monogenic inheritance in 12 parental backgrounds and digenic inheritance in one background. This suggests that either one of the two recessive genes may be common in peanut germplasm, and that crosses could be expected to segregate in simple monogenic ratios. When the proportion of genes from F435 is reduced through backcrossing to less than 0.8%, fatty acid composition remains similar to the original F435 line. Organoleptic and agronomic characteristics do not appear affected by the fatty acid composition change. Given the simple inheritance, lack of background genetic effects, and lack of apparent undesirable linkages, incorporation of high oleic acid into peanut cultivars should be straightforward.