OBJECTIVE To evaluate which is the best method to determine the left ventricular ejection fraction in heart transplant recipients: radionuclide ventriculography or gated SPECT, compared with echocardiography as the gold standard method. METHODS A prospective, transversal, observational, and open study including all orthotopic heart transplant recipients between January 1, 1993 and December 31, 2010 was realized after signed Informed Consent, and we performed echocardiography, radionuclide ventriculography and gated SPECT in 14 patients. Normal value for left ventricle ejection fraction was considered 50% in all the methods. RESULTS Fourteen heart transplant recipients were considered for the study. Two patients were excluded because of arrhythmic heartbeat at the time of gated SPECT acquisition and two by being newly transplanted. The mean left ventricle ejection fraction was: echocardiography: 69.9%;gated SPECT: 60%; radionuclide ventriculography: 61.1%. The sensitivity of gated SPECT was 75% and 100% for radionuclide ventriculography. Specificity could not be obtained because our population was very small and there were no false negatives. (All the echocardiography results were over 50%). CONCLUSIONS It was concluded that despite our small population, the gated SPECT was a useful tool in the evaluation of heart transplant patients due to its functional and prognostic information, besides offering myocardial perfusion imaging.