Introduction: Elderly is one of the most sensitive stages of life, and in the near future, a high percentage of the population is made up of the elderly. This period of life is often associated with an increased risk of chronic illness. The aim of this study was to determine the incidence of chronic diseases and its impact on the quality of life of the elderly.

Methods: In this cross-sectional study in 2018, 203 elderly subjects were selected through a multi-stage sampling method in elderly of Kahrizak sanatorium in Tehran. The history of chronic diseases was collected through checklist and face-to-face interviews. Quality of life assessment was performed using standard quality of life questionnaire (SF36). Data were analyzed using independent t-test and chi-square in SPSS software version 18.

Results: The results showed that 167 subjects aged 82.22% had at least one chronic disease and the quality of life of people with chronic diseases was significantly lower in all areas than in healthy subjects (P > 0/05).

Conclusion: The findings of this study indicate the high prevalence of chronic diseases in the elderly and its impact on the quality of life of the elderly. Therefore, it is necessary to focus on the elderly and take appropriate measures to improve the quality of life of this group of people.