By the indirect immunofluorescent technique, sera from patients with Alport's syndrome showed a reaction with the basement membrane of the capillary wall of glomeruli and peritubular vessels and nearby interstitial tissue of normal monkey and mouse kidney as a substrate. It also revealed bright staining to the matrix surrounding the clusters of EHS tumor cells and stromal tissues. These reactions were caused by autoantibodies present in these sera. These findings were supported by the detection of antilaminin, nidogen and anti collagen type VI in the sera by ELISA method. These evidences suggest that the Alport's patients developed stage of autoimmunity. The exact causes were not so clear, but seemed to be due to multiple factors.