We performed catheter closure of a patent ductus arteriosus with a Rashkind occluder in 51 adult patients (aged 14 to 76 years). The diameter of the ductus ranged from 2 to 13 mm (mean 4.5 +/- 2.0 mm), QP:QS from 1.0 to 2.6 (mean 1.6 +/- 0.3). The procedure was successful in 50/51 patients, in one of them at a second attempt. In one patient, the ductus could not be closed even with additional occluders. This patient was sent for surgery. In two patients with a large ductus, two Rashkind umbrellas were implanted simultaneously. Immediately after ductus closure, there was a residual shunt in 40/50 patients decreasing to 26/50 after 20 min. Two of the patients with a residual shunt suffered from haemolysis. In 16 patients, the residual shunt disappeared spontaneously within some months. In 15 patients, additional occluders (a second occluder in 12, a third occluder in one, and a fourth and fifth occluder in another) were implanted during the initial procedure or during follow-up. All patients were followed until angiography proved complete closure of the ductus. At the time of the last follow-up angiogram, the ductus was occluded in 49/50 patients; one patient refused a follow-up angiogram. Ductus occlusion with the Rashkind umbrella can be considered a technique with a high success rate and low rate of complications in adults. However, a residual shunt is not uncommon. Additional occluders have to be implanted in many patients.