[en] The πN scattering amplitude based on the nonlinear sigma-model through the one-loop approximation of perturbation theory is calculated. The dispersive approach is adopted in this calculation and the suitable subtractions are made by explicitly examining the asymptotic behaviors of the imaginary parts of the scalar amplitudes A/sup +-/(s,t,u) and B/sup +-/(s,t,u). Some restrictions on the subtraction constants are provided by the crossing symmetry and low energy theorems. The nonlinear sigma-model is nonrenormalizable in the conventional sense. However, in the exact chiral symmetry limit, the above procedure (namely, symmetry arguments plus low energy theorems) leaves only one arbitrary parameter up to one-loop level. Unitary partial wave amplitudes are then obtained by constructing the first diagonal Pade approximant for the perturbation series. The s and p-wave phase shifts are then computed and compared with recent experimental analyses