A national multi-centre study was performed to investigate the prevalent use of alternative medicine, or non-proven therapies, among Norwegian cancer patients. Of 911 patients invited to take part in the study 642 were included in the final analysis. Among the 630 assessable patients, 20% had been or were current users of non-proven therapies. In the northern most and western parts of Norway the most preferred alternative methods are healing by hand and faith healing, while herbs, vitamins, diets and Iscador are popular in the central and southern parts. Use of nonproven therapies is common in the northern part of the country. Prevalent users are middle-aged patients with long-standing symptomatic disease and former users of non-proven therapies for nonmalignant disease. About 40% of the patients would like non-proven therapies to be an option in hospital. Most of the users of non-proven therapies (80%) had consulted practitioners of scientific medicine first; 15% had started treatment with non-proven therapies simultaneously. The users of non-proven therapies report having received less hope of cure (30%) from their physicians than the non-users (50%) had. Most of the users had learned about non-proven therapies from friends or relatives. Most users believe that non-proven therapies might make them stronger and relieve their symptoms. Very few patients believe in a cure (10%). Nearly 40% felt that non-proven therapies had no definite effect on them. Four patients reported adverse effects. 15 patients had been treated abroad, usually in Denmark.