OBJECTIVE: Since 1976 a number of similar transvenous atrial septal defect occlusion systems have been developed and applied to prevent surgical intervention with extracorporeal circulation and the complications involved. One of them is the so called atrial septal defect occlusion system (ASDOS-device; Dr Ing Osypka, Germany). METHOD and RESULTS: In our institution, eight ASDOS-devices were implanted in adults during the last year. In six individual cases, these devices were explanted because of thrombosis, residual shunts, deformations of the umbrella, disconnection of the system and atrial perforation with hemopericard. This occured 17-380 days after the implant. The surgical removal was uncomplicated in all cases. CONCLUSIONS: Because the complication rate of the ASDOS-device was unacceptably high, surgical repair was preferred.