HLA-DR alleles of 255 healthy northern Chinese donors and 30 IgA nephropathy (IgAN) patients were determined by using a set of 30 different sequence specific oligonucleotide (SSO) probes directed to various DRB alleles. We found that SSO typing gave high gene frequencies for the alleles DR2, DR7 and DR 9 in the northern Chinese Han donors, while we obtained significantly high gene frequency for DRw12 in IgAN, especially in those with massive proteinuria and recurrent gross hematuria, indicating that those who have DRw12 may form a high risk population of IgAN.