Background: Predicting whether extracorporeal membrane oxygenation (ECMO) treatment duration affects prognosis is important both medically and economically. We conducted a retrospective, multicenter study to better understand the outcomes of patients treated with VV ECMO for a prolonged duration, analyzing data from the Israel ECMO registry. The study included all adult patients treated with VV-ECMO due to COVID-19-induced respiratory failure. The primary outcomes were survival rates up to 180 days from cannulation. Results: One hundred and eighty-eight patients were included in the study. The median age was 50 years (IQR 42, 50) and 69% were male. Patients were mechanically ventilated for a median of 2.5 days before cannulation (IQR 0.5, 5). The mean ECMO support duration was 29.9 days, with a maximal duration of 189.9 days. Survival rate for 180 days was 56%. We found no change in survival for patients on ECMO for 14, 28, or 56 days. Every day of mechanical ventilation before cannulation correlated with an 11% greater risk for prolonged ECMO treatment (p=0.01). Conclusions: For COVID-19-induced ARDS patients treated with VV-ECMO, ECMO treatment duration did not affect mortality. The longer the duration of mechanical ventilation before ECMO cannulation, the higher the risk for prolonged ECMO treatment.