Background and Objectives: Rapid response nursing team evaluates the patients in the early stages of clinical exacerbation and prevents unexpected cardiopulmonary arrest. The present study aimed at determining the effect of rapid response nursing team on outcome of patient care in the emergency ward. Methods: This clinical trial was conducted on 714 patients at the emergency ward in selected hospitals affiliated to Alborz University of Medical Sciences, during 2013. The patients were randomly allocated to a control and an intervention group. The rapid response nursing team comprised of an intensive care nurse and an anesthesia technician, who were in the emergency on a 24/7 basis. If the patient’s clinical conditions deteriorated, they immediately attended to him, evaluated his clinical condition precisely, and took necessary nursing measures for the patients in the case group, yet those in the control group received the conventional treatment at the emergency ward. Patients’ conditions and the measures taken for them were precisely recorded for both groups and the data were analyzed using the SPSS 16 software. Results: The results of the study showed that there was a significant relationship between establishing rapid response nursing team and outcome of patient care (P = 0.028), reduced transfer to special care units (P = 0.014), and reduced level of care in the first 24 hours of admission (P = 0.001). Conclusions: Given the results, the rapid response nursing team was effective in preventing unexpected cardiovascular arrests, increased successful cardiopulmonary resuscitation, and reduced transfer of patients to special care units and higher levels of care.