d,l-Sotalol is a noncardioselective beta-blocker that has class III antiarrhythmic activity. It is often used to convert atrial fibrillation (AF) to normal sinus rhythm. Since class III agents increase action potential duration and refractoriness in atrial tissue without affecting conduction, they are theoretically considered ideal agents for the treatment of reentrant arrhythmias such as AF. We reviewed the literature evaluating the efficacy of sotalol for restoring sinus rhythm in patients with acute or chronic AF. Articles indexed on MEDLINE (1966-1996) and referenced articles not identified by MEDLINE that compared sotalol with placebo or another antiarrhythmic agent were included. Sotalol was significantly inferior to quinidine in converting AF of recent onset (< 48 hrs) to sinus rhythm. In patients with duration of AF of more than 48 hours, sotalol was significantly less effective than quinidine and comparable with placebo. Conversion rates for sotalol in all studies combined ranged from 8-49%. Published studies do not support the drug for conversion of AF to sinus rhythm. Larger well-designed studies are required to evaluate its efficacy and optimum dosage for this indication. Until further data are available, pharmacologic cardioversion with traditional class I antiarrhythmic agents may be preferable as they are effective particularly for recent-onset AF.