This review focuses first on conceptual chaos and different connotations in psychosomatic medicine, then on new perspectives on comorbidity and multimorbidity, especially from epigenetics perspective. Comorbidity is one of the greatest research and clinical challenges to contemporary psychiatry and psychosomatic medicine. Recently altered gene expression due to epigenetic regulation has been implicated in the development of multifarious mental disorders and somatic diseases. The potential relevance of epigenetics for better understanding and more successful treatment of comorbidity and multimorbidity is described.