In Japan, the complement-dependent cytotoxicity (CDC-crossmatch) test and the anti-donor antibody flow cytometric assay (FCXM) are used to evaluate presensitization among transplantation candidates. We introduced the flow cytometric panel reactive antibody method (FlowPRA) at our institution, and in this paper, we compared the results of FCXM and FlowPRA. Sera of a total of 238 patients receiving the first graft were analyzed by FlowPRA retrospectively. Specimens from 125 of these patients were also analyzed by FCXM, and the results obtained using the two methods were compared. In addition, postoperative pathological findings by graft biopsy were examined in patients with PRA class 1(+) or PRA class 2(+). (i) Class 1 antibodies were detected in 36 of the 238 patients (15%), class 2 antibodies in six patients (3%), and both class 1 and class 2 antibodies in five patients (2%). (ii) Totally 125 patients analyzed by both FCXM and FlowPRA, 28 patients (22%) who tested negative by FCXM were, however, found to be positive by FlowPRA, and 16 of these 28 patients (57%) had shown evidence of humoral rejection suspected of antibody-mediated in the early postoperative stage. A large proportion of patients who tested negative by FCXM but positive by FlowPRA experienced rejection. Thus, for detecting 'high responders' in patients receiving the first graft, use of FlowPRA to detect antibodies may be superior to that of FCXM.