Background and Objective: Cardio-pulmonary resuscitation (CPR) is performed to restore life after clinical death. CPR was formerly being used for out- of- hospital arrests. Nevertheless, it is increasingly applied for in-hospital arrests. Due to differences in speed of action of in-hospital and out- of -hospital CPRs and also numerous disease features, there are striking differences in their success rate and indexes. Attendance of expert CPR team in hospital also affects success. This study was conducted to evaluate the factors related to the success rate of CPR in Vali-e-Asr Hospital, Zanjan, Iran.
Materials and Methods: In this cross-sectional study data was collected from in-hospital CPRs in Vali-e-Asr Hospital of Zanjan during 2008. The correlations between the success rate of CPR and some factors including age, sex, illness background, the first rhythm in monitoring, the admitting ward, and time intervals (including the time intervals elapsed between patient admission and cardio-vascular arrest and between collapse and initiation of CPR, the attendance of CPR team, intubation, and cardioversion) were analyzed. 
Results: 302 cases (46% male and 54% female) were included in this study. 72 (23.8%) indicated a primary success and 10 (3.3%) subjects experienced a full success and then discharged from the hospital. After adjustment for confounding variables only three factors were found to be independently associated with a successful CPR; the time necessary for the attendance of CPR team,  lack of monitoring of the patients before the arrest and the first cardiac rhythm at the time of cardiovascular collapse.

Conclusion: Extremely experienced CPR team and their timely prompt attendance on the CPR scene was the most important factor to increase the efficiency of in-hospital CPRs. The rate of success in CPR was not dependent on cardiac monitoring and was not increased in intensive care units. It seems that delayed use of the intensive care units decreases their efficacy in the success of CPRs.