Background: Critical ill patients are at high risk of complications due to severity of medical conditions and invasive procedures like suctioning and multiple treatments modalities. Airway suction is also associated with significant complications like trauma, nosocomial infections like ventilator associated pneumonia (VAP). Objectives: The present study aimed to assess the nurse’s outcome in terms of knowledge and practices on endotracheal/ tracheal suctioning before and after implementation of protocol and to assess the patient’s outcome in terms of complications related to endotracheal/ tracheal suctioning before and after implementation of protocol and finally to find the association of nurse’s and patient’s outcome with selected variables. Methods: The study followed 'Quasi experimental with non equivalentpre testpost test control group design'. The study was conducted in a selected hospital of NCR, Delhi from May 2014 to December 2014. The sample size was 60 for nurses and 145 for patients divided in control and experimental group. The tools used were 'Nurse Outcome Measurement Sheet' (Knowledge questionnaire and objective performance evaluation checklist on endotracheal suction practices) and 'Patient Outcome Measurement Sheet' (2 complications related to endotracheal suctioning: Tracheobronchial haemorrhage and ventilator associated pneumonia). Protocol on 'Suction Procedure' and was developed and validated before actual intervention. After pre test (May to August 2014) done in both groups, the intervention i.e protocol on suctioning was administered to experimental group subjects through structured teaching program over the period of 1 week. The post test was done on nurses and patients in both groups after a gap of 1 month of intervention (October to December 2014). P value <0.05 was considered statistically significant. Results: It revealed that there was significant increase in knowledge scores in all domains (Significant in hand washing, suction management and overall knowledge scores). The performance (compliance rate to the procedure steps) also improved from 52% in control group to 77% in experimental group after the intervention. There was a significant association of nurses outcome with demographic variables like education and experience at the level p<0.05. For patients' outcomes, experimental group subjects had lesser number of complications than control group (tracheobronchial hemorrhage and VAP) with p<0.05, after administration of protocol. VAP rate decreased significantly from 35.2 to 15.87 per 1000 ventilator days. Patient's outcome had a significant association with duration of invasive ventilation, suction duration and frequency of suction at the level p<0.05. Conclusion: The protocol was effective in improving both nurse's and patient' outcome.