The objective of this study was to assess the prevalence and health effects of vertebral deformities in men and women. The study was carried out as part of the cross-sectional baseline phase of The Rotterdam Study, a prospective population-based cohort study of residents aged 55 years or over of a district of Rotterdam, The Netherlands. The prevalence of vertebral deformities according to a modification of the Eastell method and concomitant functional impairment were assessed in a random sample of 750 men and 750 women. The prevalence of moderate (grade I) vertebral deformities was 8 and 7% in men and women, respectively. For severe deformities (grade II), these percentages were 4 and 8%. In men, the prevalence of both moderate and severe deformities increased with age. In women, however, the prevalence of moderate vertebral deformities remained constant, opposite to a marked increase in severe deformities. Moderate vertebral deformity was significantly associated with impaired rising in men only. Severe vertebral deformity was associated with a significantly increased risk of general disability and the use of a walking aid in both men and women, impaired bending in men, and impaired rising in women. It is concluded that (1) vertebral deformities are only slightly less common in men than in women from the general population and (2) severe progression with age occurs in women only and (3) severe vertebral deformity is, particularly in men, related to functional impairment.