Background: The aim of the study was to determine the effectiveness of scenario based simulation on safe surgery upon behavioural outcomes among staff nurses. Methods and Materials: A true experimental approach was adopted for this study. The study included 96 staff nurses selected by total enumerative random sampling technique. The selected samples were randomly allocated to control and experimental group by odd and even method systematic random sampling. The present study was conducted at Apollo Hospitals, Chennai, and Tamil Nadu. An extensive review of literature and guidance by experts laid foundation to the development of background variables proforma of staff nurses, structured knowledge questionnaire and the OSCE observation checklist. The data collection tools were validated and reliability was established. Data collection for main study was conducted after two weeks of pilot study. Pre-test assessment was done by using predetermined and pretested tools. The Scenario based simulation on Safe Surgery in the Operation Theatre was conducted as three days program, which consisted of basic concepts about surgery preoperative preparations, identification of adverse events, and the use of safe surgery checklist as three phases Sign in , Time out phase, and Sign out and Students responsibility on Safe Surgery in the Operation Theatre was taught through power-point presentation, lecture cum discussions on first Day (8hrs), skill station with demonstration and return demonstration done on Second day (8hrs). The post-testlevel of knowledge was assessed by structured questionnaire and level of skill was done on Third Day (8hrs) by OSCE (Objective Structured Clinical Examination) method. The level of acceptability was assessed after seven days of the intervention among the experimental group of students. The data obtained was analyzed using appropriate descriptive and inferential statistics. Results: There was a significant difference in post-test mean knowledge scores on scenario based simulation between control (10.86 ±4.73) and experiment group (18.97 ± 2.17) of staff nurses (t=10.29 at p < 0.001). Conclusion: The present study reveals that scenario based simulation on safe surgery is considered as a suitable method to improve the behavioural outcomes among staff nurses.