In previous studies on HLA antigens in patients with Takayasu disease, we found a statistically high frequency of haplotype Bw52-Dw12. Clinico-pathological conditions of this disease observed for 85 +/- 3 months were compared between 29 patients with (positive group) and 39 patients without this haplotype (negative group), among 82 patients with Takayasu disease. Blood sedimentation rate and C-reactive protein exhibited statistically significant high figures in the positive group as compared with those in negative group, while no difference were seen in rheumatoid arthritis test, antistreptolysin-0 titer, anti-DNA antibody, levels of circulating immune complexes, platelet aggregation, although all revealed high levels in the positive group. Pulmonary disorders were more frequent in positive group. Fourteen patients (48%) in the positive group and 5 (13%) in the negative group had abnormalities in the aortic valve (p less than 0.01). In 14 patients in the positive (38%) and 5 in the negative (13%) groups, the systolic blood pressure was over 140 mmHg (p less than 0.01). Four patients in the positive (17%) and one in the negative groups (3%) were blind (p less than 0.01). These data suggest that in patients with a haplotype of Bw52-Dw12, there is a greater likelihood of an active inflammatory state and a rapid progression of these morbid conditions.