There is a widespread belief that cancer is caused, at least in part, by aberrant mental processes. A corollary of this belief is that cancer may be cured by the application of the mind. These ideas are fostered in Australia by a popular book You can conquer cancer by Ian Gawler, a veterinary surgeon who attributes, at least in part, the development and subsequent cure of his own cancer to such processes. Critical examination of these beliefs finds evidence in their support to be lacking. None the less, many patients with cancer in this country follow the book's advice, often on the basis that it "at least can do no harm". While some patients may be aided to come to terms with their disease and to lead more fulfilling lives by taking up meditation and the positive approach to living that is described in the book, it also contains recommendations about orthodox treatments, life-style and diet which, if adopted uncritically, could be quite detrimental. The potentially harmful effects of accepting such unproved ideas about cancer need to be known more widely. Furthermore, because his ideas are making such an impact on the day-to-day treatment of cancer in this country, Gawler owes it to the community to justify, with evidence, his claims that by meditation patients with cancer may be enabled to achieve a cure of their disease in a way that is unattainable with orthodox medical treatment alone.