The objectives were to investigate the treatment and clinical characteristics of patients referred for cardioversion in Spain and to compare them with those reported in the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) and RACE (RAte Control versus Electrical cardioversion) studies. The prospective study involved 1515 consecutive patients with persistent atrial fibrillation who were referred for cardioversion at 96 Spanish hospitals. Half of the patients were being treated with Vaughan-Williams group-I or -III antiarrhythmic drugs. The most frequently used approach to anticoagulation was to administer dicoumarins 34 weeks before and after cardioversion. Our patients were younger than those in the AFFIRM and RACE studies. Compared with AFFIRM patients, our patients had a lower prevalence of previous embolism, ischemic heart disease, hypertension, diabetes, and systolic dysfunction. Compared with RACE patients, our patients had a lower prevalence of ischemic heart disease and previous embolism, but a slightly higher prevalence of hypertension and diabetes. We conclude that patients referred for cardioversion in Spain clearly had a lower cardiovascular risk profile than those in the AFFIRM study, and appeared to have a lower risk profile than those in the RACE study.