Background: Studies have shown that increased body weight and obesity may be associated with an increased risk of arrhythmic events. However, studies conducted in patients with implantable cardioverter-defibrillator (ICD) have found that low body mass index (BMI) is associated with higher mortality. The aim of this study is to evaluate the effect of obesity on the risk of arrhythmic events, hospitalization and death in patients receiving ICD therapy for primary or secondary prevention. Methods: The study was designed as a single-center prospective and observational. Patients with BMI <30 kg/m2 were classified as non-obese and patients with ≥30 kg/m2 as obese. The primary endpoints were all-cause mortality, cardiac mortality, and cardiac rehospitalization. Results: Among the total of 340 patients, 78.2% were male, 21.8% were female, and the mean age of the patients was 60.9 years. Among all patients, there were 30.6% normal weight, 47.4% overweight and 22.1% obese patients. AF recording was significantly higher in obese patients compared to the normal weight patient group (p=0.02). Shock, appropriate shock, and liquid load sensing were statistically higher in obese than non-obese patients (p = 0.042, p=0.011 and p=0.007). In the primary prevention group, all-cause mortality and cardiac mortality rates were lower in the obesity group (p=0.022, p=0.037). Conclusion: Our findings showed that although cardiac arrhythmic events are more common in obese patients, mortality and hospitalization events are less common in obese patients. These findings are consistent with the reverse epidemiology that has been demonstrated previously between obesity and mortality.