Context: Very-long-chain n-3 polyunsaturated fatty acids(omega-3 PUFAs) from fish are thought to reduce risk of sudden death, possibly by reducing susceptibility to cardiac arrhythmia. Objective: To study the effect of supplemental fish oil vs placebo on ventricular tachyarrhythmia or death. Design, Setting, and Patients: The Study on Omega-3 Fatty acids and ventricular Arrhythmia(SOFA) was a randomized, parallel, placebo-controlled, double-blind trial conducted at 26 cardiology clinics across Europe. A total of 546 patients with implantable cardioverter-defibrillators(ICDs) and prior documented malignant ventricular tachycardia(VT) or ventricular fibrillation(VF) were enrolled between October 2001 and August 2004. Patients were randomly assigned to receive 2 g/d of fish oil(n=273) or placebo(n=273) for a median period of 356 days(range, 14-379 days). Main Outcome Measure: Appropriate ICD intervention for VT or VF, or all-cause death. Results: The primary end point occurred in 81(30%) patients taking fish oil vs 90(33%) patients taking placebo(hazard ratio[HR], 0.86; 95%confidence interval[CI], 0.64-1.16; P=.33). In prespecified subgroup analyses, the HR was 0.91(95%CI, 0.66-1.26) for fish oil vs placebo in the 411 patients who had experienced VT in the year before the study, and 0.76(95%CI, 0.52-1.11) for 332 patients with prior myocardial infarctions. Conclusion: Our findings do not indicate evidence of a strong protective effect of intake of omega-3 PUFAs from fish oil against ventricular arrhythmia in patients with ICDs. Context: Very-long-chain n-3 polyunsaturated fatty acids (omega-3 PUFAs) from fish are thought to reduce risk of sudden death, possibly by reducing susceptibility to cardiac arrhythmia. Objective: To study the effect of supplemental fish oil vs placebo on ventricular tachyarrhythmia or death. Design, Setting, and Patients: The Study on Omega-3 Fatty acids and ventricular Arrhythmia (SOFA) was a randomized, parallel, placebo-controlled, double- blind trial conducted at 26 cardiology clinics across Europe. A total of 546 patients with implantable cardioverter-defibrillators (ICDs) and prior documented malignant ventricular tachycardia (VT) or ventricular fibrillation (VF) were enrolled between October 2001 and August 2004. Patients were randomly assigned to receive 2 g / d of fish oil ( Results: The primary end (range, 14-379 days). Main Outcome Measure: Appropriate ICD intervention for VT or VF, or all-cause death. point occurred in 81 (30%) Patients taking fish oil vs 90 (33%) patients taking placebo (hazard ratio [HR], 0.86; 95% confidence interval CI], 0.64-1.16; P = .33). In prespecified subgroup analyzes, HR was 0.91 95% CI, 0.66-1.26) for fish oil vs placebo in the 411 patients who had experienced VT in the year before the study, and 0.76 (95% CI, 0.52-1.11) for 332 patients with prior myocardial infarctions. Conclusion: Our findings do not indicate evidence of a strong protective effect of intake of omega-3 PUFAs from fish oil against ventricular arrhythmia in patients with ICDs.