Introduction: A current global concern is the increase in the aging population and longevity of humans and the emergence of chronic diseases, treatment costs, and the length of hospital stay in elderly. This study aimed to evaluate and compare the costs and length of stay of elderly and middle-aged patients hospitalized in Tehran's Milad Hospital, during year 2012.

Methods: This cross-sectional study was conducted on a population involving 36 327 middle-aged and elderly people, who were randomly selected from 400 patients. Data analysis was performed using the SPSS 16 software.

Results: The sample included 231 cases and 169 elderly individuals, who were middle-aged. The findings showed that there was a significant difference between the costs of hospitalization among elderly adults and their stay in hospitals (P <0.05).

Conclusions: The results of this study as well as the increasing number of seniors in the coming decades indicates that it is necessary to align with the rising costs of health policy issues and major changes to fix the problems of the elderly hospital stay.