Effects of post-hot isostatic pressing (post-HIP) on the elastic properties, strength and fracture toughness of different commercial alumina-based ceramics was investigated. The materials were presintered ceramics with alumina contents of 94, 97 and 99%. HIP was performed using a Mo or graphite furnace in a wide temperature range to establish regimes which allowed attainment of the best combination of mechanical properties, e.g. ultimate bending strength, Weibull’s modulus, fracture toughness and modulus of elasticity. The results are discussed in relation to microstructure development.