The resistance to cavitation erosion of Ultra High Molecular Weight Polyethylene (UHMWPE) coatings with two molecular weight 0.6 and 10.5Mg/mol was tested in a hydrodynamic tunnel during 98h at a flow velocity of about 90m/s. This polymer is known to have an excellent wear resistance. These materials were processed by sintering on a metallic substrate textured by electron beam melting to ensure mechanical interlocking. UHMWPE with molecular weight 10.5Mg/mol has an exceptional resistance to cavitation erosion superior to that of stainless steel A2205 whereas UHMWPE with molecular weight 0.6Mg/mol has a resistance to cavitation erosion similar to that of a conventional Nickel Aluminum Bronze alloy (in term of erosion depth). Two possible explanations are put forward for the good cavitation resistance of UHMWPE with highest molecular weight: the tensile test in semi-crystalline state shows no strain localization and, above melting temperature, the disentanglement of UHMWPE with molecular weight 10.5Mg/mol is very slow unlike the UHMWPE with molecular weight 0.6Mg/mol which tends to flow.