Background and Objectives: Progress of all sciences in various fields, especially medicine and health in the 20th century have resulted in increased longevity and subsequent increase in the elderly population. Healthy lifestyle is doubtlessly one of the important factors in increased longevity. The aim of this research was to determine lifestyle and its affecting factors in the elderly over 85 years in Qom province.   Methods: The present study was performed as a descriptive-analytical study in the elderly over 85 years covered by supporting centers and organizations of Qom province in 2015-2016. Initially, sampling was carried out by proportional stratified sampling, followed by simple random sampling method with α=95%. The sample size with the mean score of 148±12.8, was determined to be 143 according to previous studies. Data were analyzed using t-test and ANOVA.   Results: In this study, the mean score of lifestyle was estimated 141.8±14.8, which was higher in men (148.16±11.47) compared to women (137.26±15.41), and p=0.001. Two subjects (1.38%) had unfavorable lifestyle, 117 subjects (81.25%) average lifestyle, and 25 (17.36%) favorable lifestyle.   Conclusion: The results of this study showed that lifestyle status was average in the elderly of Qom province, which healthy lifestyle can be improved by more social supports from all organizations, organs, and appropriate training for the elderly and their relatives.