Background & Aim: Human Immunodeficiency Virus (HIV) prevalence is increasing, and this disease has become a crisis for the modern world. Today, the survival of patients has been increased, such that HIV is considered a chronic disease. So, Paying attention to health-promoting intervention is necessary. Thus, the current study aims to determine the effect of educating lifestyle based on the Pender model on health-promoting behaviors in HIV patients. Methods & Materials: In this randomized clinical trial study, 70 HIV patients who had inclusion criteria were selected and then divided into intervention and control groups randomly. The intervention group received 6 one-hour education sessions weekly based on Pender lifestyle (nutrition, physical activity, stress management, spiritual growth, interpersonal relationships, and health responsibility). A demographic questionnaire and HPLP2 were used, which were completed by both groups before the intervention and 8 weeks after the intervention. Chi-Square, Fisher, Independent t, and ANCOVA statistical tests and SPSS 16 software were used to analyze data. Results: results showed that there was no significant difference in various dimensions of health-promoting lifestyle between two groups before intervention. However, intervention group scores for nutrition (28. 08± 6. 23 vs. 23. 58± 6. 04), physical activity (22. 26± 6. 46 vs. 16. 39± 6. 09), stress management (25. 03± 5. 14 vs. 19. 96± 6. 41), spiritual growth (29. 49± 6. 11 vs. 25. 45± 8. 54), interpersonal relationships (29. 17± 6. 14 vs. 23. 11± 7. 45) and health responsibility (28. 36± 6. 06 vs. 23. 89± 5. 74) were significantly higher than control group 8 weeks after intervention. Moreover, the total score of health-promoting behaviors had a significant difference in the intervention group compared to the control group (166. 7± 28. 43 vs. 134. 5± 35. 68, p<0. 001). Conclusion: Based on the findings, it can be said that educating lifestyle based on the Pender model causes HIV patients to use health-promoting behaviors, which are recommended as a useful theory-based program for managers and providers of health services.