Non-perturbatively improved quenched hadron spectroscopy

We make a quenched lattice simulation of hadron spectroscopy at β=6.2 with the Wilson action non-perturbatively improved. With respect to the unimproved case, the estimate of the lattice spacing is less influenced by the choice of input hadron masses. We study also the effects of using an improved quark mass in the fits to the dependence of hadron masses upon quark masses.