The purpose of this study was to determine the prevalence of wedge-shaped abrasion defects in the teeth of an adult Swiss population. 980 letters explaining the study were sent to randomly selected subjects. 391 persons (40%) belonging to two age groups (26-30 and 46-50 years) were checked for frequency and severity of wedge-shaped lesions on all buccal tooth surfaces. Furthermore patients were asked about dietary and prophylactic habits as well as other factors possibly relevant to this study. The frequency of severe wedge-shaped defects was 19.1% in the younger, and 47.2% in the older age group, with a mean of 3 affected teeth per person (pooled age group). On average, 34.8% of all patients suffered from tooth hypersensitivity. 84.6% of the examinees with wedge-shaped defects complained of hypersensitivity at these sites. It is concluded that wedge-shaped defects cause considerable problems to more than one third of the population, and that such lesions are often combined with hypersensitivity of affected teeth.