From October 1984 to June 1991, 1,549 endomyocardial biopsies (EMB) were performed on 122 patients submitted to a Cardiac Transplant procedure (CT) at the Hospital Puerta de Hierro in Madrid. All biopsies were performed with the long sheath technique and the King bioptome. A total of 8,707 specimens were obtained, of which 7,311 (83.97%) were considered adequate for pathological examination. We did not find significant differences between the internal jugular (83.21%) and the femoral vein (84.82%) approaches. About 20% of the samples were not adequate for pathological evaluation after the fifth procedure performed on the same patient. There has been no deaths in our group. One patient (0.06%) had right ventricular perforation with tamponade that required surgical treatment. Two patients (2.98%) presented coronary fistulae related to EMB. The percent of other minor complications was less than 0.5%. EMB is mandatory for the control of rejection in the first year after cardiac transplantation, and has shown to be a reliable and safe method in experienced hands.