Donor-recipient incompatibility (D + R -) for HLA-DQ1, but not for -DQ2 or -DQ3, is associated with an adverse effect on cadaver kidney graft survival. Until now, however, DQ1 recipients of DQ1-negative kidneys (D - R +) have not been differentiated from DQ1-identical donor-recipient pairs (D + R +) and splits of DQ1, DQ5 and DQ6, have not been studied in that respect. From our data (480 transplantations performed from January 1980 to December 1990), three donor-recipient DQ combinations (D + R +, D - R +, D + R -) were formed for each of four DQ specificities (DQ2, DQ3, DQ5, DQ6). As DR-DQ linkage disequilibrium is well conserved in caucasoid individuals, DQ specificities were inferred from the associated DR specificities. Graft survival rate (%) was significantly lower for the DQ5 D + R - and the DQ6 D - R + combinations when compared with the other corresponding DQ combinations, whereas no significant difference was observed between the DQ2 and DQ3 combinations. In conclusion, if DQ1 plays a prominent role in kidney graft survival, the effects of its splits appear dissociated: DQ5 could be a marker of high antigenicity and DQ6 a marker of high responsiveness.