Background: Chest physical therapy plays an important role in increasing Pao2 and SaO2 among ICU patients which is considered as a good indicator for the general improvement of the patient besides decreasing ICU staying and costs. Purpose: To figure out the effect of chest physical therapy on oxygen saturation and partial pressure of arterial oxygen. Patients and Method: Thirty patients post MV, their age ranged from 50 to 60 years old were recruited in this study. The patients were selected from ICUs of Kasr al Ainy hospital, Faculty of Medicine, Cairo University. The patients received chest physiotherapy (percussion, vibration, manual hyperinflation), positioning and upper and lower limbs exercises. Results: Increase in Pao2 and SaO2 in addition to decreased incidence of chest infection and decreased ICU stay. Conclusion: The results of this study support the importance of chest physiotherapy on increasing SaO2 and Pao2, decrease ICU duration and decrease health care costs.