Uncertainties in the production and propagation of cosmic rays in the Milky Way

We discuss the main sources of uncertainties in the calculation of the positron and antiproton top of the atmosphere spectra using models including diffusion and convection or reacceleration. We show that, even including uncertainties, the models that include diffusion and convection are more consistent with existing measurements. The next generation experiments like PAMELA will help to reduce the uncertainties in the values of the main free parameters of the models, thus improving our knowledge of the origin and propagation of cosmic rays.