Egg yolk was partially replaced (0, 25, 50, 75, and 100%) with octenyl succinic anhydride (DSA)-modified potato starch in a reduced-fat mayonnaise formulation to curtail the problems associated with high cholesterol and induced allergic reactions. The physicochemical properties included parameters such as: pH, fat content, and emulsion stability of the formulations analyzed. The samples with 75% and 100% egg yolk substitute showed the maximum emulsion stability (>95% after two of months storage), and they were selected according to cholesterol content, particle size distributions, dynamic rheological properties, microstructure, and sensory characteristic. A significant reduction (84-97%) in the cholesterol content was observed in the selected samples. Particle size analysis showed that by increasing the amount of DSA starch, the oil droplets with the peak size of 70 µm engulfed by this compound became larger. The rheological tests elucidated that in the absence of egg yolk, DSA starch may not result in a final product with consistent texture and that the best ratio of the two emulsifiers (DSA starch/egg yolk) to produce stable reduced-fat, low cholesterol mayonnaise is 75/25. The microscopic images confirmed the formation of a stable cohesive layer of starch surrounding the oil droplets emulsified in the samples selected.Keywords: octenyl succinic anhydride; cholesterol; mayonnaise; particle size distributions; rheological characteristics; microstructure.Practical Application: The egg yolk has been partially replaced (0, 25, 50, 75,100%) by octenyl succinic anhydride (DSA)-modified potato starch in a reduced-fat mayonnaise formulation. The pH, fat content, cholesterol content and emulsion stability, particle size distributions, dynamic rheology, microstructure properties of the formulations were analyzed and the results indicated that 100% substitution of egg yolk may not be desirable because of large droplet size, low consistency and poor sensory scores. The best ratio of the two emulsifiers to produce stable reduced-fat, low cholesterol mayonnaise would be 75/25.