Background and aim: Cardiac arrest is a leading cause of mortality worldwide and has multifactorial aetiology. Timely cardiopulmonary resuscitation (CPR) and early defibrillation remain the cornerstone intervention to optimize the outcome and survival rates. Outcome after cardiopulmonary resuscitation in Emergency department (ED) have been extensively studied in western world, but data from developing countries is sparse, particularly in India, its understudied and there is paucity of literature, despite the progress made in the science of cardiopulmonary resuscitation. So, our study aims at studying the outcome of cardiopulmonary resuscitation based on return of spontaneous circulation (ROSC), survival to hospital admission, survival to hospital discharge, neurological outcome according to Modified Rankin Scale (MRS) in the emergency department of AIIMS. Patients and method: This was a prospective observational study with sample size of 233 cases who presented in cardiac arrest or went into cardiac arrest while undergoing treatment in the Emergency Department and underwent cardiopulmonary resuscitation. Sample size of convenience was used for the study and we enrolled all adults more than 18 years who underwent CPR in emergency department of main AIIMS as well as the J.P.N apex trauma centre, AIIMS. Data collection extended during a period from July 2018 - April 2020. Data were collected based on a proforma, which in turn was based on cardiopulmonary resuscitation events including sociodemographic profile, location of arrest, initial arrest rhythm, etiology of arrest, drug administered and various interventions, immediate outcome, final outcome and Modified Rankin Scale for those discharged alive. Outcome was measured with respect to return of spontaneous circulation (ROSC), survival to hospital admission, survival to hospital discharge, neurological outcome according to Modified Rankin Scale (MRS). The cases were followed up during the complete course of hospital stay death or discharge. All statistical analysis carried out by using SPSS statistical software. Data presented in Mean (SD)/Median (Minimum-Maximum) and frequency percentage as appropriate. Other appropriate statistical analysis carried out as per requirement of objective. P value less than 0.01 was considered statistically significant. Results: Total of 233 cases were recruited for the study, out of which 28.8% of cases were in the age group 18-34 years, mean age was found to be 46Y + 16.79. Males were more than females with a sex ratio of 2.1:1. Out of 233 cases, 182 cases (78.1%) where in-hospital cardiac arrest whereas rest 51 cases (21.9%) presented to ED in cardiac arrest. Among out-of-hospital cardiac arrest most common location was at home which constituted 23 cases (45.1%) and the most common mode of transport for transfer of victims to hospital was own/ rented vehicles i.e. 27 cases (52.9%). Also mean time for reaching hospital was found to be 18.6 + 12.15 minutes in OHCA. Bystander intervention in form of CPR was seen only in 8 cases (15.7%). A non-shockable rhythm i.e. Asystole and PEA, was recorded more as an initial rhythm than shockable rhythm i.e. VF and pulseless VT, in OHCA (90.2%) than in IHCA (73.9%) (p=0.00). Overall initial rhythms were ventricular fibrillation 24 (10.3%), pulseless ventricular tachycardia 33 (14.2%) asystole 107 (45.9%) with pulseless electrical activity 107 (29.6%). The most common etiology of cardiac arrest was distributive shock, 73(31.3%), followed by cardiac 40(17.2%) and respiratory/asphyxia 36(15.5%). Immediate return of spontaneous circulation (ROSC) was significantly higher in IHCA when compared to OHCA (46.7% vs 27.5%, p=0.01). Out of the 233 cases 99 cases (42.5%) had ROSC after initial attempt of CPR, of which only 83 cases (35.6%) had a sustained ROSC, but only 47 cases (20.2%) got admitted to respective wards for further care. Among those who got admitted, only 9 (3.9%) survived to hospital discharge. The final outcome, survival to hospital discharge was seen more in cases with VF (12.5%) and PEA (5.8%) f/b pulseless VT (3%) and least for asystole (0.9%). (P-value 0.00). Neurological outcome of those who survived to hospital discharge was assessed in terms Modified Rankin Scale with MRS score of 0 and 1 considered favorable outcome. In our study out of 9, 7 i.e. (3%) got discharged with good neurological outcome. Conclusion: The outcome of cardiac arrest in developing countries like India remains dismal when compared to western world. Lack of bystander CPR and weaker under-utilised and under-equipped emergency medical services (EMS) leading to a delay in receiving critical interventions were some of the important challenges. The pre-hospital care received by the OHCA victim needs immediate attention. It’s important to establish well-structured Emergency Medical Service system and conduct educational programs at the national level to improve public awareness of CPR intervention to improve survival rates. We propose development of a robust cardiac arrest registry in India, which will help filling some gaps in the existing knowledge and also facilitate future research.