Background and Aim: In order to maximize the elderly's activities and keep them at an optimized level health-promoting behaviors and being conscious of them have significant role. The present study aimed at the evaluation of health-promoting behaviors' education and their effects on the knowledge of the elderly in the geriatric nursing residences in Tehran in 2009 Materials and Methods: This semi-experimental and interventional study was carried out on 87 elderly residents in the geriatric nursing residences in Tehran selected through simple random sampling. Data gathering means was a self-designed questionnaire consisting of 62 questions covering demographic data (8 questions) and knowledge (54 questions) in six different fields including responsibility to individual health, physical activity, diet, attention to spiritual growth, interpersonal communication, and stress management. The questionnaire was completed in every nursing residence by means of interview before the education and two weeks after the last educational session. Two education sessions, each lasting 45 mins, were held in two consecutive days. The education was conducted in a group setting data was analyzed by means of SPSS software using paired t-test or Wilcoxon test. P value less than 0.05 was considered statistically significant. Results: Mean of total awareness as well as knowledge in different fields significantly increased after education. Mean score of total awareness was 62.5±9.1 vs. 85.8±8.6 in pre- and post- education evaluation, respectively (P<0.001). Conclusion: It is confirmed that the education of health-promoting behaviors influences the awareness of the elderly in geriatric nursing residences.