Skin and temporal arterial biopsies were obtained from 17 patients undergoing surgery for ruptured cerebral aneurysm, and specimens were taken from six age- and sex-matched control surgical patients. Radioactively labeled and control tissue collagen patterns were studied by interrupted polyacrylamide gel electrophoresis (PAGE), using the trisborate buffer system or by carboxymethyl cellulose (CMC) chromatography. Type III/I collagen ratios were then measured from autoradiographs of the radioactively labeled samples using the Joyce Loebl gel scanner adapted for flat bed gels. In the case of the CMC labeled material, the ratios were measured by the ratios of the summed radioactively labeled alpha 1(III), alpha 2(II), and alpha 2(I) peaks. Eleven of the 17 patients were Type III collagen-deficient while all of the six control patients had normal collagen ratios. The implications of these findings are discussed.