Background and aims: Cardiopulmonary resuscitation (CPR) success rate is an important issue for all healthcare facilities. In the present study, success rate and related factors were assessed in a hospital in Iran. Methods: This descriptive-correlational study was conducted in 2017. By using the convenience sampling, 156 patients were selected. Variables based on the In-Hospital Utstein-Style were used, which included 3 categories: patients, cardiac arrest and follow-up. Data were analyzed by SPSS 22. Results: Of 156 participants, 92 were male and the average age was 61.4±5.5 years. Most cardiac arrest occurred in night shift (43.6%). The most common cause of cardiac arrest was cancer (33%). Of 156 patients, 102 died. Results showed a significant correlation between success rate, a patient’s sex, rhythm type and medication administered during resuscitation (P<0.001). Conclusion: Success rate in our study was low in comparison to previous studies. Further attention should be paid to this issue.