In this work the rheological behaviour of aqueous alumina suspensions with solids loadings ranging from 37 to 59 vol% is studied. A complete rheological characterisation is performed by measuring under both controlled rate and controlled stress conditions to obtain expanded flow curves, and by oscillatory tests to determine the elastic moduli. A commercial polyelectrolyte was used as dispersant. The interparticle potentials are calculated considering the electrostatic and the steric contributions. The electrostatic pair potential is estimated through the determination of the elastic modulus, G’, the double layer thickness and the surface potential by using a spatial particle distribution model. The consideration of the steric potential, by using a soft spheres model, produces significant changes in the shape and values of the potential energy curves and allows predicting the stability of suspensions that should coagulate according to the DLVO equation. The colloidal stability and the rheological behaviour are correlated with the green and sintered densities of Al2O3 bodies produced by slip casting.