A novel noninvasive sensitive mean to detect cardiac rejection is described: myocardial uptake of 111In-labeled monoclonal antimyosin antibodies (MAA). All patients showing rejection at cardiac biopsy disclosed positive MAA studies. However, a large percentage of positive studies in the presence of negative biopsies were detected. This discrepancy can be ascribed to a false-negative biopsy result. During the first year posttrasplantation MAA studies are useful to predict severe rejection-related complications, but due to high sensitivity of MAA, treatment for rejection in this period must be based on biopsies, as criterium to treat for rejection on the basis of MAA scans would lead to excessive immunosuppression. After the first year of transplantation, individual patient management can ben implemented on the basis of risk stratification using MAA scans: Negative MAA scans entail an almost nil probability of detecting rejection during long-term follow-up (low-risk group), whereas positive MAA scans imply a probability of detecting near 1 episode of rejection and requirement for treatment per year. In summary, at our institution biopsies are avoided as from the first year after transplantation; after such period, MAA scans allow risk stratification and treatment for rejection based on the results of MAA scans in individual patients.