Background: Estimations of life expectancies (LE) in health and ill health are important for planning future health care support. This study aimed at quantifying whether an increased LE is accompanied by an increase in the duration of life with dementia (DemLE) in Hong Kong SAR. Methods: Two parameters from a logistic model were used to fit the overall trend of the weighted prevalence of dementia. Abridged age- and sex-specific life tables and Sullivan's method were used to calculate dementia-free LE (DemFLE) for 1998 and 2013. Results: In 2013, among elderly individuals in Hong Kong aged 65 years, men had lived with dementia for 1.8 years and women for 3.6 years. These values are similar to those for subjects aged ≥85 years, while the proportion of DemLE was much greater at advanced ages. Elderly female individuals tend to experience a greater number of years with dementia than males. Conclusion: Our results indicate although LE has increased for all older age groups over time, the increase in DemFLE has not been greater than the gain in LE, suggesting an absolute expansion of the burden of dementia to the community between 1998 and 2013. The results suggest that more caregiving resources and manpower will be needed in the future as the population ages.