Background: COVID-19 has affected millions of people worldwide. To date, efforts made to develop antiviral strategies for the treatment of COVID-19 remain underway. Respiratory viral infections predispose to co-infections which lead to increased disease severity and mortality. This study aimed to determine COVID-19 bacterial co-infection incidence and assess the severity and outcome among patients in Zagazig University quarantine ICUs. Patients and methods: This prospective cohort study was carried out on moderate and severe COVID-19 patients admitted to Zagazig University quarantine intensive care units , full history taken ,complete physical examination and vital signs with laboratory investigations ,bacterial co-infection assessment (within 48 hrs of admission ) in form of persisting fever or leucocytosis (neutrophilia) and high procalcitonin with blood or sputum cultures, follow up the patients till discharge or death. Results: Among 180 studied COVID-19 patients there was 21.1% of them had bacterial co-infection while 78.9 % were without bacterial co-infection, there was 8.9% with positive blood cultures and 16.1 with positive sputum cultures. There was significantly higher percent of severity, CPAP need and death rate among patients with bacterial co-infection ,there was statistically significant difference regarding duration of ICU stay with higher median in COVID-19 without bacterial co-infection. Conclusion: The incidence of COVID-19 bacterial co-infection among patients in Zagazig University quarantine ICUs was 21.1% with Klebsiella organism the most causative organism and there was significantly higher percent of severity and death rate among COVID-19 patients with bacterial co-infection.