The present invention relates to novel crystalline salts of Asenapine and to methods of their preparation. In particular, the invention relates to crystalline Asenapine salts of tartaric acid or succinic acid, wherein the salts are e.g. selected from the group consisting of Asenapine D, L-tartrate hydrate form A, Asenapine D, L-tartrate hydrate form B, Asenapine D, L-tartrate anhydrous form , Asenapine succinate form X, Asenapine succinate form , and Asenapine succinate form II.Furthermore the present invention relates to pharmaceutical compositions comprising the novel salts and to the novel salts for use in the treatment of psychotic diseases or disorders.