Ro(SS-A) positive female Sjögren's syndrome (SS) lupus erythematosus (LE) overlap patients are a clinically and serologically homogeneous group generally demonstrating prominent subacute cutaneous lupus erythematosus (SCLE) lesions, cutaneous vasculitis, peripheral and central nervous system disease, pulmonary disease, and a low frequency of glomerulonephritis. They commonly demonstrate rheumatoid factor, hypergammaglobulinemia, antinuclear and Ro(SS-A) La(SS-B) antibody activity. This study indicates that these patients are also immunogenetically similar, sharing a statistically significant increased frequency of HLA-B8, DR3, DRW6, DQ2, and DRw52. Sixty-three percent of these SS/LE patients possess the extended haplotype (P-value 6.0 X 10(-3); RR 9.5) HLA-B8, DR3, DQ2, DRw52. One hundred percent of this SS/LE cohort was DR3 or DRw6 (P-value less than or equal to 5.0 X 10(-3); relative risk 19.1). Fifty percent of these patients were HLA DR3/DRw6 heterozygotes (P-value 1.5 X 10(-6); relative risk 31.2). Thus, HLA-DR3 and DRw6 Ro(SS-A) positive SS/LE patients may possess a similar, if not unique, DR region DNA nucleotide sequence involved in disease susceptibility or immune regulation.