We have studied the HLA-DRB and -DQB1 alleles of 42 paediatric patients who have suffered from membranous nephropathy associated with a hepatitis B infection (HBVMN). These patients were all from the Gdansk area of Northern Poland and the disease was diagnosed by light and electron microscopy. The control population consisted of 55 healthy children, approximately age matched, from schools in Gdansk. In addition we have also analysed 40 patients chronically infected with hepatitis B, without any renal involvement, as hepatitis B disease controls. The HLA alleles were defined using PCR/SSP. As idiopathic membranous nephropathy and low responsiveness to hepatitis B vaccine have been found to be associated with DR3 in Caucasoids, our hypothesis was that the HBVMN patients would show an increase in DR3. Our results indicate that, although there is a small increase in the frequency of DRBl*0301 in the HBVMN patients (16/42 38%) when compared to the healthy controls (15/55 31%), this does not approach significance. There is a significant increase in the frequency of DQB1*0303 in the HBVMN patients vs the healthy controls, after correction for the number of antigens detected (Pc)(13/42 vs 2/55, RR=11.6, P=0.0007, Pc=0.02). A similar increase in DQB1*0303 is seen in the HBVMN patients when compared to the hepatitis controls (13/42 vs 4/40) but this is only significant before correction (RR=4.3, P=0.04).