Rheological properties depend on total solid content particularly the amount and type of protein and with higher solids content in yogurt, there is a tendency to increase G′ and G″ and thus decrease the deformation in yogurt gel. The supplementation level is, therefore, animportant factor which can alter gel structure, and affect functional properties such as water absorption (Sendra et al., 2010). Some studies have shown that addition of whey protein isolate improves the physical properties of yogurts such as viscosity (Isleten & KaragulYuceer, 2006; Sodini, Montella et al., 2005). Our study shows that supplementation increased the strength of the gel system and lentil flour had either greater or comparable effect to skim milk on the strengthening of the yogurt gel network