In the first part of the talk I will very briefly review the basic facts about scattering theory in the S-wave and P-wave channel. I will introduce the notions needed to describe low energy collisions in ultracold atoms: scattering amplitude, scattering length, scattering volume, true range and effective range of the interaction. I will then review the Efimov effect for a bosonic system. The main part of the talk will be devoted to the three-body problem for polarized fermions, close to a P-wave Feshbach resonance. I will present a two channel model useful to describe the P-wave interaction. Through numerical and analytical solutions of the model, I obtain predictions for all the physical quantities relevant for present experiments: low energy elastic and inelastic scattering properties, existence and lifetime of weakly bound trimers, atom loss rate through the three-body recombination mechanism. The model also excludes the presence of an Efimov effect in the P-wave channel. Applications and future developments will conclude the talk.