ABSTRACT. - Composition and antioxidant properties of sixteen pecan [Carya illinoinensis (Wangenh) K. Koch] cultivars grown simultaneously in a single experimental orchard in Uruguay were evaluated to characterize their nutritional properties and nutraceutical potential. The percentage of oil, moisture, ash, minerals, and proteins were determined and also the fatty acid profile. Total phenolic compounds [18-41 mg gallic acid equivalents (GAEs)/g], condensed tannin [2-12 mg catechin equivalents (CEs)/g], and tocopherols (110-163 ?g/g) contents were estimated in nut kernels. Total phenolic compounds (32-117 mg GAE/g), condensed tannins (130-357 mg CE/g), and total anthocyanins (1-3 mg 3-glucoside cyanidin/g) were also determined for pecan shells. The antioxidant activity in shells [57.15-578.88 ?mol Trolox equivalents (TEs)/g] was 5 times higher compared with the kernels (23.15-156.60 ?mol TEs/g) measured with hydrophilic ORAC. Bioactive compounds concentrations present statistically significant genetic variability between cultivars studied (p