In a study undertaken to investigate the relationship between vibration syndrome and collagen disease, 90 Japanese patients with vibration syndrome (all men aged 41-86 years) were examined immunologic abnormalities, mainly by a set of immunoserology tests. Of these 90 patients, 25 had examinations at yearly intervals for 3 consecutive years, while the other 65 underwent examinations once. The results indicate that, of all the patients studied, 10 (11.1%) gave a positive RA test, 6 (6.7%) had leukopenia, 5 (5.6%) had hypergammaglobulinemia, and 15 (16.7%) had hypocomplementemia (CH50). Worthy of particular note are the 21 patients (23.3%) who were positive for nuclear-specific antibodies (1: greater than or equal to 40) (using Hep-2 cells as the nuclear substrate), with some of them suspected of having SjΓΆgren's syndrome, progressive systemic sclerosis, or systemic lupus erythematosus. During a 3-year follow-up period, 10 (40%) of 25 patients exhibited rising titers of nuclear-specific antibodies with conversion to seropositivity for these antibodies. The facts that the positivity rate for nuclear-specific antibodies was significantly higher in these patients with vibration syndrome (23.3%) than in healthy adult men over 40 years of age (1.8%) (P less than 0.05) and that a progressive elevation of nuclear-specific antibody titer was noted in a high percentage of the patients were suggestive of some causal relationship between the appearance of nuclear-specific antibodies and the use of vibrating tools.