The diagnosis of active lymphocytic myocarditis by the use of the endomyocardial bioptome is at present a hotly debated topic. However, the question of whether lymphocytes reside in the myocardium of individuals without systemic or cardiac disease has rarely been addressed, but is obviously of critical importance in helping to resolve this issue. Therefore, we examined endomyocardial biopsies obtained from 86 young heart disease-free cardiac transplant donors at the time of transplantation. Foci of inflammatory cells were found in eight (9.3%) cases and by definition contained greater than five inflammatory cells per focus. The inflammatory infiltrates were predominantly lymphocytic. Based on these results and those of others, it is becoming evident that there is a normal myocardial lymphocyte population which must be reckoned with when considering the diagnosis of myocarditis, realizing the potential therapeutic implications of this diagnosis.