The effect of aggregate characteristics on rheological properties of soy protein dispersions was studied. Aggregated protein was produced by heating a solution of soybean protein isolate (SPI) at 0.04g/mL and 0.09g/mL. The higher protein concentration resulted in a larger aggregate size with a higher intrinsic viscosity and a higher accessibility of thiol groups. The protein fraction in native SPI had the smallest size and the lowest intrinsic viscosity. The same trend was observed for the shear viscosity after concentrating the suspensions containing aggregates to around 0.14g/mL. Suspensions containing aggregates that were produced from a higher concentration possessed a higher viscosity. After reheating the concentrated suspensions, the suspension from the 0.09g/mL aggregate system produced the weakest gel, followed by the one from 0.04g/mL, while the native SPI yielded the strongest gel. Our results prove that the process of soybean protein aggregation opens a new door to manipulate the gel strength of concentrated protein systems, without having to alter the concentration of the protein.