A panel of 79 individuals were typed for HLA-D/DR associated Primed Lymphocyte Typing (PLT) defined "DP"-antigens, HLA-D and HLA-DR antigens. Typing for DP-antigens was carried out with local PLT-cells. HLA-D and -DR typing was performed with all homozygous typing cells and all DR-antisera included in the 8th International Histocompatibility Workshop. Assignments of DP-, HLA-D- and HLA-DR-antigens were done independently and the correlations between DP/D/DR1-8 were analyzed. The panel included random unrelated individuals, and individuals previously found to have one or no identifiable HLA-D antigen (B). In the random group, 80% of the individuals were assigned to possess the same antigen with the 3 techniques, while this was only the case in 46% of B-group individuals. The overall correlation coefficients, r, for the antigens HLA-Dw/-DR/DP1-8 were 0.95 (DP/D), 0.94 (DP/DR), and 0.89 (D/DR). There is a remarkably strong correlation between HLA-D and -DR typing results concerning D/DR1-8, in particular in random individuals. It is possible to select PLT-cells that give typing results which are almost identical to those of HLA-D and -DR typing. When discrepant results were seen, HLA-DR was in general "broader" than DP which in turn was broader than HLA-D, indicating that it may be possible to split HLA-DR/DP1-8 into more "narrow" specificities.