Granular deposits of IgA are known to occur in the walls of superficial vessels in apparently healthy skin of patients with primary IgA nephropathy, Henoch-Schönlein purpura, or alcoholic liver disease, but the specificity of the finding is still a matter of debate. We investigated the disease specificity of these deposits in the skin of patients with kidney and liver diseases. The sensitivity of the finding for the diagnosis of primary IgA was 75%, the specificity was 88%. The sensitivity for the diagnosis of alcoholic liver disease was 71%, but the specificity was only 60%. The specificity for the diagnosis of Henoch-Schönlein purpura, primary IgA nephropathy, or alcoholic disease (in a group of 1,030 patients with various diseases) was 94%. Immunoelectron-microscopic investigation showed the IgA deposits localized within the endothelial cell and in the subendothelial rim.