Background : Studies have shown an association between obesity and total mortality in patients with and without coronary artery disease. Less is known regarding the impact of obesity after cardiac arrest. Obese survivors of ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA) may have worse outcomes than nonobese patients due to resuscitation challenges, long-term risks of cardiovascular disease, and other comorbidities. Methods : All patients who presented with a VF OHCA in Rochester Minnesota from November 1990-September 2006 were included. Patients were classified by weight (BMI <25, 25–30, >30). ICD shocks for VF/VT were determined by review of subsequent device interrogations. Results : 226 patients (age 63.7±13.5) were treated for VF OHCA with an average call-to-shock time of 6.3±1.8 minutes. 99 patients (44%) survived to hospital discharge with neurologic recovery. Data to calculate BMI were available in 213(95%). There was no difference between the relative distribution of body weight between the hospital survivors [<25(32%), 25–30(37%), >30(31%)] and nonsurvivors [<25(32%), 25–30(44%), >30(28%)], p=0.711. There was no difference in ICD implantation rates between weight groups (p=0.251). The patients were followed for an average of 5.8±4.4 years. The 5-year survival was 80±5%. 5-year survival was lower in underweight/normal patients [<25, 71% (63–79) compared to heavier patients (25–30:88% (82–94), p=0.001]. The survival difference persisted after adjustment for age (p=0.02). Malignancy was the most common cause of death in the underweight group. The 5-year survival free of ICD shocks was 61±7% with no weight-based difference in shocks. Conclusion : There was no apparent weight-based influence on resuscitation survival after VF OHCA. Patients who are under to normal weight had a lower long-term survival and represent a high-risk population primarily due to noncardiac diseases.