The aim of this work is to assess the accuracy of a surface matching registration (SMR) technique for the correlation of cardiac studies in positron emission tomography (PET). Registration parameters were estimated by matching corresponding body surfaces, extracted from transmission studies, aligned to the PET emission images to be correlated. The accuracy of the SMR technique in this specific application was assessed by computer simulations, phantom experiments and on clinical PET data. Registration accuracy was evaluated in relation to the body surfaces (external, internal and the combination of the two) used by the SMR method. Better results were found when matching shaped and irregular surfaces such as internal lung contours. The robustness of the method was verified for different counting statistics recorded in transmission images. A clinical validation of the SMR method was performed on fluorine-18-deoxyglucose PET cardiac studies.