For ethical and practical reasons, in this study the antiarrhythmic potential of fish oil was evaluated in patients free from complex ventricular arrhythmias and severe heart failure. Although subjects without overt structural heart disease had ventricular arrhythmias that were not associated with an increased risk for sudden cardiac or coronary death, recent data suggest that frequent VPCs in patients similar to our study population may reflect subclinical cardiac disease amenable to the multiple beneficial actions of n-3 fatty acids. The potential and safety of fish oil as a treatment for more complex cardiac arrhythmias or arrhythmias in higher risk patients with more severe heart disease deserve further study.