The effect of an early-, mid-, or late-season planting date on the fatty acid chemistry of four high oleic acid, one mid oleic acid, and five normal oleic acid peanut (Arachis hypogaea L.) genotypes was evaluated over a three year period. Oleic acid was also compared to other fatty acids and to indices of oil quality. High-oleic genotypes included SunOleic 97R, UF98326, UF99621, and 88x1B-OLBC1-6-1-3-1-b2-B with a mean oleic acid content between 77.8 and 82.5%. Florida MDR98, a mid-oleic cultivar, was intermediate in oleic acid chemistry (59.8-68.0%). The normal oil chemistry lines (Georgia Greene, Andru93, Florunner, 86x13A-4-2-3-2-b3-B, and UF97102) had an oleic acid content between 50.0 and 59.0%. The ratio of oleic to linoleic (O/L) was 18:1 to 51:1 for high-oleic lines and 1.7:1 to 3.5:1 for normal genotypes. When analyzed as a split-split plot in time, year had a highly significant effect (P < 0.001) on the eight main fatty acids, iodine value, ratio of unsaturated to saturated fatty acids (U/S), and percentage of saturated fatty acids. Thus, data were analyzed separately by year. Although genotypic effects were highly significant each year, planting date influenced oil chemistry in two of three years. During both 1999 and 2000, 11 of 12 variables were influenced by planting date and by genotype x planting date interactions. Iodine values were approximately 75 for high-oleic lines compared to 90-95 for normal genotypes. The highest correlations occurred for oleic acid (18:1) and linoleic acid (18:2) (r = -0.996) and for oleic and palmitic (16:0) acids (r = -0.959). Oleic acid was also inversely related to iodine value (r = -0.978) and to percentage saturation (r = -0.841).