The wear behaviour of a nanobainitic cast steel: 0.76C-2.08Si-0.74Mn-0.79Cr (wt. %), isothermally treated at different temperatures, 250 and 300°C; have been investigated by pin on disk test in dry conditions. The tests were carried out at different loads: 2, 7, 12 and 15 N. The results show that the wear rate is higher when the isothermal transformation temperature and load increases. Also, at low loads adhesion, oxidation and abrasion are the main wearing mechanisms, while at high loads contact fatigue becomes dominant. The results are related to the microstructural differences produced by the change in the isothermal temperature of the heat treatment.