The theology of dense suspensions of P-casein micelles is investigated at pH 6. For a given temperature, the viscosity increases dramatically at a critical concentration (C-c) of about 100 g/L due to jamming of the micelles. For a given concentration close to and above C-c, the viscosity of dense suspensions decreases strongly with increasing temperature because C-c increases. The suspensions show weak shear thickening followed by strong shear thinning. At lower pH, that is, closer to the isoelectric point, spontaneous gelation is observed, which is favored by lowering the temperature and addition of sodium polyphosphate. The gelation process is studied at pH 5.5 by theology and light scattering.