Objectives: To evaluate clinical characteristics and prognosis of patients presented with acute coronary syndrome (ACS) that developed ventricular tachyarrhythmia VTA and to analyse it according to the period of presentation. Background: VTA is an infrequent yet serious complication of ACS. There is limited data regarding the incidence and prognostic implications of VTA in the last decade as compared with the previous decade. Methods: We evaluated clinical characteristics, major adverse cardiovascular events, short and long- term mortality of patients hospitalised with ACS who were enrolled in the Acute Coronary Syndrome Israeli Survey (ACSIS) during the years 2000-2016. Patients were classified into three groups: no VTA, early VTA (≤48 hours of onset) and late VTA (>48 hours of onset). Data were analysed according to the period of presentation: early vs late period (years 2000-2006 and 2008-2016 accordingly). Results: The study population comprised 15,200 patients. VTA occurred in 487 (3.2%) patients. Early VTA presented in 373/487 (77%) patients and late VTA in 114/487 (23%) patients. VTA’s, occurring in ACS patients were associated with increased risk of in-hospital, 30-days, 1-year and 5-year mortality rates during both early and late periods compared with no VTA. Moreover, late VTA was associated with the highest mortality rate with up to 65% in 5-year follow up (P <.001). Nevertheless, late VTA was associated with a lower mortality rate in the late period compared with the early period. Conclusions: Any VTA following ACS was associated with high short- and long-term mortality rate. However, over the late period, there has been a significant improvement in survival rates, especially in patients with late VTA. This may be attributed to early and invasive reperfusion therapy, implantable cardioverter-defibrillator implantation and better medical treatment.