In this issue of the Journal, Hershberger and colleagues presentdata from a multicenter trial of immunosuppression in cardiac-transplantrecipients showing that daclizumab, a monoclonal antibody againstthe interleukin-2 receptor, reduces the overall incidence ofcellular rejection.1 In discussing these data, I will focuson three areas: the role of and difficulty in carrying out randomized,controlled trials of immunosuppressive regimens in heart-transplantrecipients, the end points one is forced to choose in performingsuch studies, and the clinical relevance of the primary endpoint of cellular rejection, as well as the possibility of anegative outcome.