Catheters were developed that can be fixed in the prostate gland by self-expanding parts for use in PDR brachytherapy. Daily CT-scans were made to investigate the magnitude of catheter displacement. The mean absolute displacement during the 3 day treatment was 1.2 mm. The resulting minor alterations in dose-volume parameters were of no clinical importance. © 2006 Elsevier Ireland Ltd. All rights reserved.