Different levels of shortening in cookies (10%, 20% and 30% by weight) were replaced with 20% jet-cooked oat bran, also called Nutrim oat bran (OB), to prepare cookies with fewer calories. The cookies containing Nutrim OB were investigated in terms of rheological and physical properties and compared with a control. As more shortening was replaced with Nutrim OB, a decrease in the diameter and an increase in the height of cookies were observed. The increased moisture content from Nutrim OB caused a decrease in the dynamic viscoelastic properties of cookie dough. Squeezing flow method showed shear thinning behaviours in all cookie doughs. Also, the elongational viscosity of cookie dough decreased significantly with more replacement of shortening with Nutrim OB. The rheological properties of cookie dough during baking indicated that all of the samples had similar types of viscoelastic characteristics during baking. However, the cookies containing more Nutrim OB exhibited more elastic properties which resulted in a decreased cookie diameter. There was no significant difference in cookie hardness among samples with up to 20% shortening replacement but the cookies became lighter in colour as the Nutrim OB content was increased.