Background: the mobility and exercise play an important role in the recovery of functional status, early mobilization of critically ill patients who are admitted to intensive care units. This should be performed based on safety criteria that were categorized as follows: cardiovascular, respiratory, neurological,inaddition rehabilitation of critical ill patients depends on various factors, such as previous physical strength and functioning, level of cooperation, and devices connected. The Aim of the current study is to assess correlation between initiating time of mobilization and cardiopulmonary stability among critical ill patients. Design: A descriptive research design was utilized in the current study. Subjects of this study are consecutive purposive sample who are admitted in previous intensive care units at Minia University and who are related to inclusion criteria. Setting: the study was carried out at two critical care units (traumatic intensive care unit and neurosurgery care unit). Tools:  two tools were developed by the researcher, the first tool is Patients' structured questionnaire (personnel characteristics, patient's medical information data) and the Second tool is patient's cardiopulmonary assessment sheet, and one standardized scale (Perm scale). Results: showed that most of mobility practice (93.3%) were not done by I C U nursing staff except only two practices which were done for most of the studied sample (91.7%) as to move into standing position and to use walker or assistive device respectively and it was revealed that majority percentage for potential mobility barriers among study's sample who had pain constituted (93.3%). Conclusion: the early mobility for critical ill patients after admission in intensive care unit was a rapid effect on selected cardiopulmonary instability parameters and improvement on patients out comes. Recommendation: conscious patients and nurses should be educated about early mobility exercise; Post admission to intensive care unit had a positive effect on muscle strength and cardiopulmonary stability.