It has been reported previously that HgCl2 chronically injected in the BN rat induced a biphasic renal disease. During the first stage, anti-glomerular basement membrane antibodies appeared and during the second stage, an immune-complex type glomerulonephritis was observed. In the present study, a systemic immune disease is described. During the first stage, antibasement membrane antibodies were observed in various extrarenal structures. Their localization has been found to depend mainly on the characteristics of the endothelium. During the second stage, immune-complex type deposits containing IgG and C3 were found in most vascular structures. Their localization did not apparently depend on the endothelial characteristics. Among the organs tested the lung was most often spared. The occurrence of immune complex deposits was found to depend on the dose of HgCl2 injected: deposits were absent in some high dose HgCl2-injected rats but they were very numerous in low dose HgCl2-injected rats. These deposits probably have a pthogenic role although no major histological lesion could be found. This model may help to explain immune complex type deposits in systemic diseases.