Background: Despite the importance of early defibrillation in shockable cardiac arrest management that can affect the outcome, our Egyptian studies are very little in comparison with European and American updated studies. Aim: to improve Cardio pulmonary resuscitation protocols quality to give high rate of success of resuscitation protocols influencing ultimate outcome. Patients and Methods: Randomly selected 81 patients who are diagnosed as cardiac arrest either in hospital or out of hospital were included. They received advanced life support (ALS) protocol, and the effect of defibrillation time was assessed. Results: our study scope on the relation between early defibrillated shockable patients and time when first shock delivered, 25 patients received shock around 5 minutes (recorded by timer) from the beginning of resuscitation of confirmed cardiac arrest. The outcome as well as survival rate were the highest among patients who defibrillated early (n= 25). Of them, 23 patient got Return of Spontaneous Circulation (ROSC). However, among patients who defibrillated late (after 5 minutes, n=35), only 20 patients got ROSC. Conclusion: Our study showed that early defibrillation is the most important key to a successful outcome of inhospital patients with cardiac arrest who need defibrillation.