Background and aims: Knowledge about Health-Related Quality of Life (HRQoL) in advanced age is sparse. This study investigated to what extent mobility factors explained older people's HRQoL when age, gender and functional ability (ADL) were controlled for. Methods: Subjects were 1128 people aged 60-96 participating in a Swedish longitudinal multi-center cohort study. Besides descriptive and correlation statistics, a three-tier multiple logistic regression analysis was performed, which included the ADL scale, mobility tests and items, with physical and mental HRQoL as outcome variables. Results: In the models containing the control variables, functional ability was found to be associated with both physical and mental HRQoL. In the models including both functional ability and mobility factors, the importance of functional ability remained for mental but not for physical HRQoL. The mobility factors were found to have a stronger negative influence on HRQoL, i.e., physical and mental, than functional ability in itself. Conclusions: For optimal identification of various types of disabilities and their impact on older people's HRQoL, the ADL scale should be used together with more target-specific tests of disabilities. However, in certain situations, it appears that one mobility factor alone - the ability to walk - has the capacity to pick up changes in both physical and mental HRQoL. Thus, it is important that healthcare professionals should focus activities toward maintaining older people's mobility as a means of enhancing their HRQoL.