In 1999, the European Organisation for Research and Treatment of Cancer (EORTC), being a European pioneer in the field of cancer research as well as in quality assurance (QA), launched an Emmanuel van der Schueren fellowship for QA in radiotherapy. In this paper, the work that has been done during the first E. van der Schueren fellowship is reported, focusing on four phase III EORTC clinical trials: 22921 for rectal cancer, 22961 and 22991 for prostate cancer and 22922 for breast cancer. A historical review of the QA programme of the EORTC Radiotherapy group during the past 20 years is included.