Background: The aging of the world’s population will determine global health trends. According to the 2021 report of the Capital City Health Department, the average life expectancy of the Mongolian population is 71.3 years (male 67.3, female 76.7), the difference between male and female life expectancy is 9.4 years, and elderly people aged 60 and over account for 8.1% of the total population. The report also shows that 6.5% of all outpatient visits are for people aged 60-64, and 9% are for people aged 65 and over, which means that they do not receive adequate health care services. Therefore, it is im portant to increase the access to and quality of health care services provided to the elderly in order to improve their health and quality of life. Comorbidities that are common among the elderly are one of the pressing issues in the health sector. Aim: We aimed to study the prevalence and risk factors of multi-morbidities among older adults (aged sixty years and over) in urban and rural areas. Materials and Methods: To accomplish our aim, we conducted 156 lifestyle related questionnaires and 18 health related questionnaires among 720 older people in Ulaanbaatar city and rural areas, and created the database. Pearson correlation coefficient was used to determine the relationship between the quantitative influence of factors using single and multi-fac tor linear (β-coefficient) and binary logistic regression (odds ratio, CI 95%) methods, and p value less than 0.05 was con sidered statistically significant. The Apriori algorithm in SPSS was used to determine the relationship between multiple chronic diseases in the elderly people. Results: The prevalence of comorbidity was higher in urban areas (48.1%) and rural areas (51.9%), and ageing (urban areas OR: 2.45, 95% CI: 0.9-6.2; rural areas OR: 6.35, 95% CI: 1.47-27.4, P<0.01) was a risk factor of multi-morbidi ties. Multimorbidity is defined as the presence of 2 or more chronic conditions, and 3, 4, and 5 chronic conditions were co-occurred to older adults with chronic conditions, 28.7% (165). 11 common patterns of relationships in urban areas and 18 common patterns of relationships in rural areas (support (A→B)>3%, confidence (A→B)>30%, lift (A→B)>1) were determined. Conclusion Multimorbidity was different in urban and rural areas, 11 common patterns in urban areas and 18 common patterns in rural areas were determined. It has shown that the prevalence of multimorbidity was different in urban and rural areas.