Walnut press-cake, a rich source of phenolics, is a by-product of walnut oil processing. In this study, the effects of walnut press-cake on cake quality, health-enhancing substances and antioxidant activity were determined. Wheat flour was replaced with walnut press-cake at 0, 5, 10, 15 and 20% levels. Results show that specific volume, firmness, resilience, cohesiveness, chewiness, crust a, b and crumb L, b values reduced with increasing walnut press-cake levels. However, polyunsaturated fatty acids, tocopherols, total phenolic content and antioxidant capacity of cakes increased. Antioxidant capacity measured by 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) assays of cakes prepared with 20% walnut press-cake were 10.04-and 5.56-fold, respectively, greater than that of the cake without walnut press-cake. Cakes added with 15% walnut press-cake to wheat flour had the highest scores in all sensory parameters. Walnut press-cake can be successfully incorporated into cake formulation to improve sensory properties and antioxidant activity of the cake.