- Background: Loneliness is widespread among older adults, in particular among those who are chronically ill and functionally limited. The aims of the paper are: (i) to examine the extent to which users of day care centers experience loneliness compared to their peers who are non-users; and (ii) to explore the relationships between length of use and frequency of weekly attendance at day care centers and loneliness among users of day care centers. Methods: A case-control study was used with a sample of 817 respondents of whom 417 were users of 13 day care centers and 400 were non-users, matched by age, gender, and family physician in the southern region of Israel. Data collection included face-to-face interviews using a structured questionnaire. Results: The vast majority in both groups (79.3% and 76.3%, respectively) reported moderate to severe levels of loneliness. Perceived economic status and self-rated health were the most significant variables in explaining loneliness. No significant differences were found between users and non-users of day care centers in the level of loneliness. Attendance at day care centers, as well as length and frequency of use, had no significant association with loneliness. Conclusion: More research, which will include quasi-experimental and longitudinal research designs, is necessary to examine the causal relationships between attendance at day care centers and loneliness. This can provide information on the effectiveness of day care centers in reducing loneliness among frail older adults.