In the paper we examine some mechanical properties of the unstabilised zirconia sinters, such as Vickers hardness and fracture toughness. The sinters were prepared using two step sintering technique. It is the first time, when two step sintering is used to process unstabilised zirconia nanopowders. As a preparatory experiment, a microstructure evolution of the sinters was determined in order to select the temperatures T1 and T2 of two step sintering. The samples were sintered below the monoclinic to tetragonal transformation temperature, using several T1 and T2 combinations and different sintering times. The sinters were compared in terms of density, grain size, Vickers' hardness and fracture toughness. The samples were sintered to full density, showing a grain size of 95 nm, Vickers hardness of 11 GPa and fracture toughness of 5.32 MPa∙m0.5.