Anti-GBM disease has been associated with the HLA genes of the major histocompatibility complex (MHC) in previous serological studies, with an increased incidence of HLA-DR2 in patients. In this study, 36 patients with anti-GBM disease were genotyped by restriction fragment length polymorphism (RFLP) analysis using cDNA probes for DRB, DQA, and DQB. The frequency of HLA-DRw15(Dw2), a split of DR2, was significantly increased in the patients compared with the controls (63.9 per cent versus 23.3 per cent, chi 2 = 22.4, p(corr) less than 0.0001), and all but one of the patients were positive for either DRw15(Dw2) or DR4 (p less than 0.0001). The frequencies of the remaining DR antigens were not decreased randomly, with a significant decrease in DR7 in the patient group (chi 2 = 8.6, p(corr) less than 0.05). The closely linked gene HLA-DQw6 was found to be significantly increased in frequency in the patients compared with the controls (p(corr) less than 0.0001). No correlations could be made between the genetic data and clinical features of the disease.