Nonoperative closure of patent ductus arteriosus (PDA) by means of Ivalon plugs (according to the technique of Porstmann) was performed in 101 patients. Sixty-five patients were symptomatic, the Q p/Q s ratio exceeded 1.5 in 56 patients, and pulmonary hypertension (mean pulmonary artery pressure greater than 20 mmHg) was present in 50 patients. In 100/101 patients the PDA could be closed successfully. Ninety-nine patients were without any evidence of residual left-to-right shunt. In one patient a hemodynamically insignificant left-to-right shunt was found with color Doppler echocardiography. Complications were pulmonary embolism due to plug dislocation in two patients (12th and 14th patient; 2 and 7 weeks after the procedure, respectively). One of these patients underwent elective surgery with patch closure of the ductus and removal of the embolized plug. In the other patient the ductus was successfully closed with a second larger plug while the first plug was left in a peripheral pulmonary artery. Surgical revision of the femoral artery was required in six and blood transfusion in two patients. Deep venous thrombosis developed in two patients. During follow-up (total follow-up time more than 200 patient years) no late complications were observed. In conclusion, transfemoral catheter closure of PDA by means of Ivalon plugs is an effective method. It is applicable to adolescents and adults with a low complication rate. The ductus can be closed without residual left-to-right shunt. Long-term results are excellent.