Vinyl chloride (VC) monomer can induce a scleroderma-like syndrome in a proportion of workers exposed to it during production of polyvinyl chloride. As part of a 5-year follow-up study HLA A, B, and DR antigens and anti-centromere and anti-scleroderma-70 antibodies were determined in 44 such workers. 21 of these had severe and 23 mild forms of vinyl-chloride disease. 50 patients with "classical" scleroderma and 148 healthy hospital workers acted as controls. 11 of the 21 patients classified as having severe VC disease were DR3 positive, and 8 of these had both B8 and DR3 antigens. None of the 23 patients with mild disease carried either antigen. The HLA-antigen frequencies in VC disease mirrored those found in scleroderma (raised DR5 frequency and increased linkage disequilibrium between B8 and DR3). There were, however, significant differences in the frequency of autoantibodies in the two conditions.