OBJECTIVE To determine the success rate and safety of percutaneous closure of patent ductus arteriosus (PDA) with a detachable coil. METHODS Forty-one children with small- to moderate-size PDA (maximum diameter < or = 4 mm) underwent percutaneous coil occlusion. The results were assessed by angiography and echocardiography. The mean age was 2.0 +/- 1.3 years (range 0.6 to 5.6 years); mean weight was 10.0 +/- 3.4 kg (range 4.5 to 18.0 kg). The mean minimum diameter of the PDA was 1.7 +/- 0.6 mm (range, 0.5 to 4.0 mm). RESULTS The occlusion device was inserted in 39 of 41 patients (95%). The mean coil/PDA ratio was 3.41 +/- 1.1. We observed angiographic cessation of blood flow through the PDA after coil insertion in 18 patients; 18 patients had residual shunt, 3 mild shunt and 2 moderate shunt. No complications were observed during the procedure. Thirty-five patients showed absence of blood flow through PDA 24 hours after coil occlusion by echocardiography. The other four patients with residual shunt showed flow cessation after 2 months in two patients and after 6 months in the other two. Failure of coil insertion in two patients was due to detachment of the pulmonary edge of the coil, which was subsequently removed in one, and due to coil migration in the other, both patients underwent surgical PDA closure. Mean follow-up at 29.5 +/- 16.5 months showed no residual blood flow through the occluded PDA, except for one patient. CONCLUSIONS Our results, as many others, suggest that PDA coil occlusion is a safe, effective, and cheap procedure. PDA coil occlusion should be the elective method for PDA closure in patients older than 6 months of age with small- to moderate size PDA (< or = 4 mm). The procedure in newborn infants and patients with larger PDA must be made with a different type of occlusive device.