Background. Improving living conditions and increasing life expectancy have led to aging of societies. Lifestyles of the elderly and its related chronic diseases have changed by all of these factors, so this study was conducted to assess the correlation between lifestyle and chronic diseases of the elderly in Gonabad in 2019. Methods. In this descriptive-analytical study, 600 elderly residents of Gonabad were selected randomly from population covered by the three community health centers of Gonabad. Data was collected using lifestyle and its related chronic diseases questionnaires. These questionnaires were completed by interview method. The data were analyzed using independent t-test, paired t-test, ANOVA, Pearson test and chi-square test (SPSS software version 23). Results. Of the 600 participants, 321 (53.5%) were male and 279 (46.5%) were female with a mean age of 47.68 years. The lifestyle of the elderly was 0.7% favorable, 36.2% relatively favorable and 62.7% unfavorable. The prevalence of diseases in the elderly was heart disease 31.3%, blood pressure 42.8%, heart attack 8.2%, stroke 4.8%, diabetes 17.8%, cancer 6.5%, shortness of breath 17.3%, malnutrition 5.2%, constipation 16.3%, arthritis 27.3%, osteoporosis 21.3%, depression 12.8%, urinary problems 20%, vision problems 12.3%, hearing problems 12.2% and sleep problems 14%. There was a significant relationship between lifestyle and gender (P=0.001) so that the lifestyle average value of men was higher than women. There was also a negative and significant relationship between age and lifestyle (r=- 0.34) (P<0.001) so that with increasing age, lifestyle mean value decreased. Mean value of lifestyle based on educational levels was significant difference. Conclusion. Due to the high percentage of chronic diseases, low lifestyle in the elderly and relationship between lifestyle and chronic diseases of the elderly, screening and monitoring of chronic diseases should be given more attention. Also, improving the lifestyle of the elderly should be considered. Practical Implications. There is no clear and accurate information about the lifestyle of the elderly and related diseases in different parts of the country, so this study helps to better understand the lifestyle of the elderly and related chronic diseases, and by knowing them, strategies can be And designed more effective interventions to improve the lifestyle of the elderly in order to prevent and control chronic diseases threatening the elderly.