The aim: Research aim is the evaluation of return of spontaneous circulation (ROSC) ratio among the individuals with out-of-hospital sudden cardiac arrest (SCA), depending on the so-called Telephone Cardiopulmonary Resuscitation (TCPR). T-CPR is based on live instruction given by the dispatcher to incident witness, who is performing CPR efforts until the EMS team arrives on scene. Material and methods: Research was based on the analysis of 782 entries (from EMS documentation) which recorded SCA and CPR. Emergency call voice recording has been rehearsed for each case, in order to confirm the capability of recognizing SCA and providing T-CPR instructions. Data was divided into two groups and the results have been compared. The ROSC ratio for both groups (“T-CPR” and “No T-CPR”) were analyzed along with the type of incident location. Results: The research has shown that 26,4% of all SCA cases researched ended up with the ROSC. In 94% of cases the dispatcher had succeeded in encouraging the witness to perform CPR with telephone instruction (T-CPR) until the EMS team has arrived. In the “T-CPR” group, 28,7% of cases have ended with ROSC. In the “No T-CPR” group, 19,7% of cases have ended with ROSC (28,7% vs. 19,7%). Conclusions: The T-CPR should be utilized by dispatcher in the form of uniform protocol. In the process of training dispatchers there should be special emphasis on the skill of recognizing SCA upon receiving a call. The evaluation of SCA recognition, T-CPR undertaken and ROSC ratio may be an effective indicator of quality monitoring within the State Emergency Medical System.