BACKGROUND Out-of-hospital cardiac arrest (OHCA) is a significant clinical challenge for emergency medical systems worldwide. The first step towards ensuring patient survival is achieving return of spontaneous circulation (ROSC). The purpose of the study was to analyze the cases of OHCA to which HEMS teams were dispatched. MATERIAL AND METHODS We performed a retrospective analysis of all HEMS calls in Poland for cases of OHCA between 1 January 2011 and 31 December 2016. Data were obtained from medical records maintained by the Polish HEMS. RESULTS The total number of responses to cases of OHCA was 2447. Of this total, 308 cases were excluded from the study as the patient was found not to have cardiac arrest or was confirmed dead. ROSC was achieved in 1119 cases, including 335 cases where ROSC occurred before the arrival of the HEMS team. In the group studied, ROSC was achieved more commonly in women, in patients younger than age 40 years, in CA cases of cardiac origin, and in cases with shockable rhythms (p<0.05). CONCLUSIONS The study results are consistent with global trends in terms of OHCA incidence and the effectiveness of CPR performed on scene. The study also demonstrates that HEMS dispatch to OHCA cases is justified both as a means of providing assistance to EMS teams on scene and as the first choice.