The purpose of this study was to investigate the efficacy, safety and cost-effectiveness of intravenous and oral propafenone in the conversion of paroxysmal atrial fibrillation propafenone to sinus rhythm. We analysed two groups of 100 consecutive patients (pts) treated because of propafenone with duration < 48 h. The first group was treated with intravenous PFN (bolus of 70 to 140 mg) and the second group was treated with oral PFN (300 to 600 mg). These 2 groups were comparable in age, sex, evidence of CAD, hypertension, mitral valve disease, history of hyperthyroidism and the level of K+ at admittance. Conversion to sinus rhythm was achieved in 64 (64%) pts who received i.v. propafenone and in 77 (77%) who received oral propafenone (p < 0.05). We conclude that oral and intravenous propafenone is safe in the termination of propafenone. Oral route of administration appears to be superior to intravenous because of greater efficacy and cost-effectiveness.