Starting in January 1995, we performed heart transplantation, randomly using standard and bicaval techniques. In the latter technique, the anatomy of the right atrium is maintained, since the venae cavae are anastomosed. In 38 patients who received heart transplantation with bicaval anastomosis, 339 endomyocardial biopsies (EMB) were performed. EMB was done under echocardiographic control in 309 cases, whereas the remaining 30 were done under fluoroscopy. When EMB was echo-guided there was one major complication, namely right hemothorax in a 29-year-old man, who had had heart transplantation one week before, and this required surgical exploration. Other complications, correlated to venipuncture were: left hemothorax in a 65-year-old woman determined by arterial puncture, treated by means of chest tube drainage; pneumothorax (1 case). Echocardiographic guidance during EMB allows a better choice of biopsy site, reduces the risk of damaging cardiac structures and allows immediate monitoring of heart performance. Moreover the risk of X-ray exposure to both patient and operators is reduced. In any case, because the superior vena cava suture line is not visualized by two-dimensional echocardiography, if the bioptome cannot be introduced easily through superior vena cava, fluoroscopic control should be immediately applied, particularly in the early post-operative period when cicatrization is not complete.