The amyloid deposits in 21 renal biopsy specimens were subjected to a detailed immunohistochemical analysis using a panel of antibodies against recognised constituents of tissue amyloid. This was a retrospective study of material originally submitted during the investigation of various renal abnormalities and studied by a routine protocol including histochemistry, electron microscopy, and immunofluorescence. The presence of an amyloid was confirmed in all 21 cases. Seventeen cases contained P component and either amyloid A (AA) (11 cases) or an immunoglobulin light chain associated amyloid (six cases). Four cases contained amyloid material with unusual immunohistochemical findings; one case had AA and P-component (PC) in the interstitium, one case had lambda light chain and beta-2 microglobulin, one case had kappa light chain and Clq, and one case had lambda light chains only. It was possible, therefore, to identify precisely the amyloid constituents and thereby "type" the amyloid by immunohistochemical means. The availability of the antibodies used and their application using these techniques could simplify the confirmation of clinically suspected amyloidosis.