The aim of this study was to assess the effect of physiotherapy on ventilator dependency and lengths of intensive care unit (ICU) stay. Patients were divided into two groups. The control group, which received standard nursing care, was a retrospective chart review. The data of control patients who were not receiving physiotherapy were obtained from the hospital records. The intervention group was prospectively taken into the chest physiotherapy program. This study was planned on mechanically ventilated patients who were admitted to a six-bed multidisciplinary internal medicine intensive care unit of the university hospital. A total of 510 patients who were hospitalised in the ICU were included in the study. Demographics, diagnostic profiles, co-existing chronic diseases, respiratory parameters on admission, patient's overall severity by Acute Physiology and Chronic Health Evaluation II score, patient outcome, duration of stay in ICU, duration of ventilator support, and complications were assessed. The extubation time and length of ICU stay were compared between the two groups. Control patients had a longer period of ventilator dependency than the intervention patients and this difference was statistically significant (P less than 0.05). It was noted that the resulting length of stay in the ICU was significantly lower in the intervention group than in the control group (P less than 0.05). Although the patients had similar diagnoses and physical features, the length of stay in the ICU was significantly lower in the intervention group. The results show that physiotherapy has a great impact on ventilatory dependency and length of stay in the ICU.