Decisions about when to start, how long to continue and how to end cardiopulmonary resuscitation (CPR) are important in the management of these critically ill patients. The aim of our study is to determine the factors that can help in the early prediction of patients in whom spontaneous circulation can be restored during CPR. Patients who had arrest due to nontraumatic causes were included in the study. The patients whose spontaneous circulation (ROSC) was restored in the emergency service and who were hospitalized in intensive care were included in ROSC (+) group, while the patients who did not have ROSC and who became exitus were included in ROSC (-) group. Patients’ demographic characteristics, chronic diseases, places of arrest, admission laboratory values and possible causes of death were compared between ROSC groups. This study was conducted with the retrospective examination of 309, 118 (38.2%) female and 191 (61.8%) male, cardiopulmonary arrest cases. ROSC was achieved in 94 (30.4%) of the patients who underwent CPR. It was found that a 0,1 unit increase in pH value increased the probability of ROSC by 38% [OR: 1,38 (95% CI: 1.22-1.55), p<0.0001], while multivariate logistic regression analysis showed that it could be an independent predictor of ROSC and increased the probability of survival by 0,43 times [Corrected OR: 1.43 (95% CI: 1.13-1.83), p=0.0033]. It was also found with multivariate logistic regression analysis that respiratory causes could be an independent predictor of ROSC and increased the probability of survival by 2.76 times [Corrected OR: 3,76 (95% CI=1,499.53), p=0.0052]. In patients who undergo CPR, pH value in blood gas analysis and the presence of respiratory system diseases as the cause of arrest are important parameters in determining the probability of ROSC.