During the 10th International Histocompatibility Workshop (10th WS), 181 HLA MoAbs were studied using lymphocytotoxicity micro-technique (LCT) and/or enzyme immuno-assay (EIA), and their capacity to serve as typing reagents was evaluated. 129 MoAbs were tested by both techniques. Results obtained with 92 class I and 86 class II polymorphic MoAbs (10th WS) were compared to published data concerning 180 class I and 176 class II polymorphic MoAbs, listed in an HLA-MoAbs Register maintained in our laboratory. The following conclusions can be proposed: 1/HLA-A, B typing by LCT with MoAbs is possible for about 14 specificities. Some specificities are clearly recognized (HLA-A3, B8, B13, Bw4, Bw6), others are recognized as cross-reacting groups (B7+27+w22+40), others are not currently recognized by any MoAb with restricted specificity (B5, B15). Several MoAbs confirmed the existence of shared epitopes between products from a single locus (A2-A28, A25-A32), or from A and B loci (A2-B17, Bw4-A9-A32). A single HLA-Cw MoAb has been described. 2/HLA class II typing by LCT with MoAbs is more difficult than class I typing. DR2, DR3, DR4, DR5 and DR7 as well as DRw52 and DRw53 are well defined; other DR specificities are poorly or not at all defined. Particular associations (DR1+DR4, DR3+DRw6, all DR except DR7) are recognized by several MoAbs. All DQw specificities are well recognized, including new specificities defined only by MoAbs: WA (DQw4), TA10 (DQw7), 2B3 (DQw6+w8+w9). Only two HLA-DP MoAbs have been described. 3/Satisfactory results, similar to those of LCT, were obtained with EIA using lymphoid cell lines as targets. 4/Human MoAbs (12 in the Register) are satisfactory typing reagents. They could represent in the future a significant contribution to HLA typing with MoAbs.