Information disclosure is a key factor in the support for cancer patients. The European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Group has developed a questionnaire to evaluate the level of information received by cancer patients at different stages of their disease and treatment: the EORTC QLQ-INFO26. It can be used in clinical practice and research, including clinical trials. The questionnaire was developed following EORTC Quality of Life Group guidelines. The paper presents the data on 133 patients from eight countries. The resulting EORTC QLQ-INFO26 questionnaire includes four sub-scales on information regarding their cancer, medical tests, treatment and other services and several single items. Copyright © 2006 John Wiley & Sons, Ltd.