Objective: The aim of this field study (the “Fourth German Oral Health Study”) was to obtain representative data on caries (DMFT index), periodontitis (CPI) and prosthetic status in the German population and to evaluate changes in the oral health of the German people as compared with the findings of the Third German Oral Health Study conducted eight years previously. Basic research design: The study took the form of a population-representative cross-sectional survey with random samples, and was complemented by a questionnaire to reveal sociological as well as behavioural data. Participants: The age cohorts in the present study were 12-year-olds (children), 15-yearolds (adolescents), 35- to 44-year-olds (adults) and 65- to 74-year-olds (senior citizens). Results: All age groups showed considerable improvements in oral health with respect to caries. Of the children, 70.1 % were free of dentine caries and the mean DMFT value was 0.7. In adults and senior citizens both the DMFT value and the number of missing teeth and edentulousness declined. With regard to periodontal conditions, increasing prevalence of moderate and severe findings was recorded in adults and senior citizens, owing probably to the larger number of natural teeth remaining in the oral cavity. Conclusion: The study documents a distinct improvement in oral health in the German population. Interrelated with the higher numbers of remaining natural teeth a higher prevalence of moderate and severe periodontal conditions in German adults and senior citizens was observed. Key words: Adolescent, adult, aged, child, dental caries, epidemiologic study, oral health, periodontitis, prosthodontics.