SUMMARYWe prove that the Wigner equation is well-posed in L p (R 2n ) for some potential V . From the formalism established by Markovich, we show the completeness of wave operators for the Wigner equation in L 2 . Using estimations proved by Castella and Perthame, on the one hand, and the L p → L q estimations for the Schr odinger group, on the other hand, we prove the existence of the wave operators in L 2;p spaces.