This review presents a critical evaluation of the literature on health effects in long-term occupational exposure to whole-body vibration. To assess the relative weight of each epidemiologic study, a scoring procedure has been used, according to the quality of exposure data, effect data, study design and methodology. The most frequently reported adverse effects are: low-back pain, early degeneration of the lumbar spinal system and herniated lumbar disc. No study reached an adequate score on all criteria of evaluation. Nevertheless, because most studies show a strong tendency in a similar direction, it may be concluded that long-term exposure to whole-body vibration is harmful to the spinal system. The results do not yet permit firm conclusions on exposure-response relationships. Further epidemiologic research, particularly of high-risk groups, is needed.