This study was aimed to assess the effectiveness of Simulation on Hospital Emergency Code Programme upon the Competency of Nurses in Disaster Preparedness at Selected Multi Specialty Hospitals, Chennai. Methods: Study was conducted by using Quasi-experimental time series research design (with one pre-test and 2 post-tests: post-test 1 and post-test 2) at selected private College, Chennai with the Sample size of 94 who are divided into 9 teams, 10-11 students in each group. Samples were chosen by using total enumerative sampling technique. The intervention included the one day workshop on Simulation on Hospital Emergency Code Programme. Data were collected through observation method by using pretested and predetermined tools such as Background Variables proforma and observation checklist to assess the team performance of the students. Collected data were entered and analyzed using SPSS- 20. Results: Study findings revealed that, there is a significant difference in the mean scores (Team Score) of students between pre-test, post-test 1 and post-test 2 in total score (M=115.33, SD 11.64; 135.22, SD 7.22; 140.44, SD 9.76 in pre-test, post-test 1 and post-test 2 respectively) as well as in all the components such as Code Blue, Code Red, Code Pink, and Code Brown within the subjects and between subjects (p<0.001). Conclusion: Improved practice scores in post-tests than pre-test can be attributed to the effectiveness of the Simulation of hospital emergency code programme in disaster preparedness among Final year Nursing students. Therefore this intervention can be replicated in all other settings to prepare the nurses to manage the hospital emergency situations effectively and efficiently.