BACKGROUND AND AIMS: The purpose of the present study was to examine for factors related to tiredness, cross-sectionally at the age of 75 years, and factors related to subsequent onset of tiredness, from age 75 to 80 in a non-disabled community-living population. METHODS: The study is part of the prospective Nordic Research on Aging Study (NORA) on the 1914 cohort in Jyväskylä, Finland and Glostrup, Denmark. In total, 546 non-disabled older men and women participated in the cross-sectional study at age 75, and 299 persons without tiredness and disability at baseline took part in the follow-up study, from age 75 to 80. Tiredness was measured by a validated scale based on the following items: using the toilet, washing and dressing lower body, and cutting toenails. Independent variables were: social position measured by housing tenure and income, chronic diseases, use of medicine, pain, muscle strength, lung function, cognitive performance, depressive symptoms, life satisfaction and insomnia. RESULTS: Analyses of cross-sectional data showed that social position, number of comorbidities, muscle impairment, pain and depressive mood were independently associated with tiredness. Longitudinal analyses showed that onset of tiredness was significantly or marginally significantly influenced by use of more than three drugs, muscle impairment, pain and cognitive impairment. CONCLUSIONS: The present study showed that tiredness in non-disabled older adults is a result of multiple potentially modifiable factors, which may be fully treated or at least alleviated, thus increasing the well-being of the individual, as well as potentially slowing the progression of disability.