The present invention relates to trans-4-{2-[4-(2,3-dichlorophenyl)-piperazin-1-yl]- ethyl}-N,N-dimethylcarbamoyl-cyclohexylamine (cariprazine) and pharmaceutically acceptable salts and hydrates and solvates and polymorphs thereof for use in the treatment of primary negative symptoms of schizophrenia and/or predominantly negative symptoms of schizophrenia.