We have experienced 2 cases vocal cord paralysis after open heart surgery. One was a postoperatively developed right unilateral vocal cord paralysis after prosthetic mitral valve replacement with tricuspid valve annuloplasty. The other was a postoperative left unilateral vocal cord paralysis after prosthetic aortic and mitral valve replacement with tricuspid annuloplasty. They were intubated for forty-eight and seventy-two hours but after extubation complained of hoarseness, aphonia, anxiety, and ineffective coughing Indirect laryngoscopy performed at about postoperative one week, revealed partial paralysis and decreased mobility of the vocal cord. After active phonation therapy, symptoms were improved gradually and in the follow up indirect laryngoscopy, the vocal cord paralysis was improved. The symptoms were recovered completely at about postoperative one month in both. The cause of vocal cord paralysis after open heart surgery may be any retraction or stretching injury to the recurrent laryngeal nerve, especially right side, during median sternotomy retraction and open heart operation procedures. As a result, avoid of excessive spread of median sternotomy retractor and excessive manipulation and retraction of the heart during open heart procedures will reduce the occurrence of the vocal cord paralysis.