We present a 54-year-old male heart transplant recipient who developed mediastinitis caused by Klebsiella oxytoca and Veillonella species. Culture of the donor's bronchus also grew K. oxytoca and a Veillonella species. Pulsed-field gel electrophoresis revealed that the K. oxytoca isolates had identical banding patterns. This case illustrates transmission of pathogenic bacteria via a contaminated organ.