The attenuation length of proton primaries and the proton-air inelastic cross section are studied at energies E 0 10 1 5 eV by using the EAS-TOP array data. Proton initiated Extensive Air Showers, in the energy range (2 4) 10 1 5 eV and near maximum development, are selected from their N μ (E μ > 1 GeV) and N e sizes. The experimental attenuation length Λ o b s is compared with those obtained from simulations, including the full detector response, based on different interaction models (HDPM, VENUS, DPMJET, QGSJET and SIBYLL) in the frame of CORSIKA code. The proton-air inelastic cross section is also inferred by using the factor k = Λ s i m o b s /λ s i m p - a i r obtained from each interaction model.