Inulin is a natural polysaccharide with useful effects on health and functional properties, which are correlated to its average chain length. From shortchain inulin or oligofructose (2-7 units) to long-chain type (22-25 units), the solubility may be decreased but the gel forming ability are improved. The use of long-chain inulin as a fat substitute is thought to be related to its ability to form microcrystals that interact with each other forming small aggregates. Also, modified starch is frequently used as fat mimetic in low-fat foods, because of its creamy texture and creating a mouthfeel similar to fat. In the present research, the effect of modified starch (3 wt%) substituted with different types of inulin (0-10 wt% short-chain, native and long-chain) as an optimized combined mixture formulations in low-fat mayonnaise is studied in relation to chemical composition, physical stability, flow behavior, viscoelastic and sensory properties of the product. According to steady and dynamic flow curves that were described by Herschel-Bulkley and Carreau-Yasuda models, the effect of all types of inulin depends on the presence of modified starch (≥1.5 wt%) and an interrelationship was observed between type/ concentration of inulin and concentration of starch on physical stability, flow and viscoelastic behavior of various formulations. This phenomenon was more significant in samples containing higher amounts of long-chain inulin (≥5 wt%). The results of rheological and sensory analysis suggested that the use of 5 wt% long-chain inulin with 5 wt% of its short-chain and 1.5 wt% modified starch would endow properties similar to the commercial products.