Systemic thromboembolism is a severe complication in patients undergoing electrical cardioversion (ECV) for atrial fibrillation (AF). Vitamin K antagonists greatly reduce the risk of thromboembolic events, but the administration scheme before ECV is troublesome as difficulties in reaching and maintaining the target therapeutic range for 3 weeks often delay the restoration and likelihood of maintaining sinus rhythm. Low molecular weight heparins (LMWHs) do not need dose adjustment, and may be preferable in this clinical setting. In this multicentre study, the LMWH parnaparin was used at a dose of 85 anti-factor Xa U/kg b.i.d. 2 weeks before and 3 weeks after ECV of AF. In an intention to treat analysis of 102 patients, there was no systemic thromboembolism or major bleeding (0%, 95% CI 0-3.6). Two clinically relevant non-major bleeds (2.5%, 95% CI 0.7-8.8) and three minor bleeds (3.8%, 95% CI 1.3-10.6) were recorded. No heparin-induced thrombocytopenia or other major adverse events were recorded. Parnaparin appears effective and safe for thromboprophylaxis of elective ECV in patients with AF.