Loneliness is a widespread phenomenon that affects the physical and mental health of the elderly. One of the main issues for the elderly is keeping the independence in daily living activities. Thus, this study was carried out to investigate the relation between the level of loneliness and Activity of Daily Living (ADL) in the elderly. This correlational study included 120 elderly aged more than 60 which were selected using convenience sampling. Data collection instruments were the UCLA-LS (University of California, Los Angeles) 37-item loneliness questionnaire and 20-item activity of daily living questionnaire. The mean score of loneliness and ADL in the elderly participated in this study was 75.4±23.9 and 62.4±15.7, respectively. A significant relationship was observed between loneliness and ADL. This study also showed a significant relation between loneliness and demographic factors such as marital status, education level, living arrangement, having close friends, hearing impairment, and using aiding devices. Regarding the growing population of the elderly in Iran and the role of loneliness in activity of daily living, the supporting and consultation role of nurses along with the ordered and organizational programming from health and wellness improving organizations is highlighted.