OBJECTIVES: The aims of this study were 1) to describe changes in self-assessed masticatory ability over a 14 year period (1975-89); and 2) to describe associations between self-assessed masticatory ability and age, dental state and some other background factors in a sample of the Swedish population in 1988/89. DESIGN: The Swedish National Central Bureau of Statistics investigates annually the living conditions of the Swedish population by means of interviews by trained persons. The data were analysed by means of stepwise logistic regression and calculation of adjusted relative risks. SUBJECTS: In the investigation in 1988/89, 12,901 people above 16 years of age participated and the response rate was 80%. RESULTS: In comparison between the investigations, the prevalence of reported impairment was lower in 1988/89 than in 1975 and 1980/81. Prevalence of reported impairment of chewing ability increased with ageing from 2% in young adults (16-34 years old) to 44% in older elderly (> 85 years old). In most age groups, edentulous people reported the highest prevalence, and dentate people the lowest. Relative risks for impaired masticatory ability, independent of age, gender and dental state, were higher for people in rural areas, with low income and living single, as well as for those with skeletal, gastrointestinal, psychiatric and tumour diseases. In the elderly, results from the logistic regression showed that some disability and psychosocial factors were also associated with masticatory ability. CONCLUSIONS: The results indicated that there was a group of elderly people who reported several functional and health problems including impaired masticatory ability.