Single-phase Fe-Nb and Co-Nb Laves phase alloys were produced by arc melting and levitation melting. By casting the levitation melted alloys in a preheated mould and subsequent slow cooling to room temperature, solid rods of 15 mm in diameter and about 100 mm length of the brittle Laves phases were obtained. Within the extended homogeneity ranges of the NbFe2 and NbCo2 Laves phases, the Vickers hardness was measured in dependence on composition. The results show that the hardness has a maximum at the stoichiometric composition in both systems, indicating defect softening. Nanoindentation measurements on a Co-Nb diffusion couple confirm the dependence of the hardness on composition. In addition, these measurements indicate that the crystal structure of the Laves phase polytype – cubic or hexagonal – seems to have no effect on the hardness. Indentation fracture toughness KIC-IF data for the different polytypes of the Laves phases were evaluated from the Palmquist cracks originating from the edges of the Vickers indentations.