The high prevalence of psychiatric disturbances in the context of medical illness and its association with worse prognostic of the last one, are the reasons for which it becomes essential that the doctor, not psychiatrist, has the skills in the use of psychopharmaceuticals. A systematic review of the literature published until January of 2006 was done, through MEDLINE, using as key-words psychiatric illness, renal illness, hepatic illness, cardiovascular illness, psychopharmacology. The reviewed studies include original articles, reviews and observational studies. 39 articles were selected for its adequacy and acquired for the accomplishment of this revision. The authors intend to review the use of the several classes of psychopharmaceuticals, its risks and benefits, according to the different medical illnesses. The first part of this article will have is focus in the area of cardiology, nephrology and hepatology.