Disclosure of the diagnosis of cancer to the patients affected has always been a controversial issue in the doctor-patient relationship. Undoubtedly this is so not only because of differences between countries and cultures, but also because there have been changes of opinion over the years. The aim of this study was to evaluate the quality and quantity of information desired by Portuguese cancer patients, and how and from whom they want to hear this information. Our sample comprised a total of 193 cancer patients, 87 men and 106 women. We found that 68.9% knew what their diagnosis was. In our sample, 74% wanted "as much information as possible, good or bad"; 85% said they wanted to know if their disease was cancer; 95% wanted to know the best or worst likely outcome of their disease; and 96.4% wanted to know the chances of getting cured. Most patients said they would prefer to be informed by physicians (92.7%) and have access to a telephone help-line, books and television. In conclusion, most patients wanted to know as much as possible about their illness and treatment, and the majority preferred to be involved in treatment decisions.