Background: Multimorbidity defined as the co-occurrence of two or more chronic conditions which is very common among older adults. The Aim of this study was to assess the effect of multimorbidity on quality of life among older adults. Research design: a descriptive analytical study was done. Setting: This study conducted at the geriatric hospital (Elshahid Elmohandes Ahmed Shawky Hospital) outpatient clinic of medicine affiliated to Ain Shams university Hospitals. Sample: A purposeful sample of 125 older adults with multimorbidity representing approximately 5 % of all patients attending at the previously mentioned setting and have the following criteria: All older adults (males and females) diagnosed with at least two chronic health diseases and aged 60 years or more. Tools: interviewing questionnaire was used which included five parts :( 1) Socio-demographic characteristics about older adults. part (2) past history about older adults. part (3) Older adults health behaviors related to multimorbidity. part (4) Quality of life assessment scale. Part (5) Cumulative Illness Rating Scale Results: The study showed that 48% of the studied sample of older adults their age ranged between 65 - < 70 years. Also, 57.6% of them are male. There was 72% of the studied sample of older adults had poor level of health behaviors. The study showed that, 73.6% of the studied sample of older adults had Endocrine-Metabolic problems, while 69.6% of them had vascular problems. Related to total quality of life, 56% and 53.6%, respectively of the studied sample of older adults had poor level of physical and psychological aspects. Conclusion: The study concluded that a highly significant negative correlation between multimorbidity and their quality-of-life in which more than half of the studied sample of older adults with multimorbidity had low level of quality of life. Recommendation: the study recommended that; increase public awareness throughout educational sessions, programs, and campaigns about multimorbidity for older adults and their families.