Cancer patients attend oncogenetic clinics so that the existence of a genetic risk can be checked and the relatives informed. The aim of this study was to describe the expectations of cancer patients about genetic counselling and their beliefs about the aetiology of their disease. A survey based on self-administered questionnaires before and after the consultation was carried out on 115 women with breast/ovarian cancer who attended one of the six French participating clinics. In 59 cases (51%), the consultees' expectations focused on the preventive options available and in 86 cases (75%) on their offspring; 87 (76%) found the consultation informative. On average, the women rated heredity and diet as lower risk factors (P < 0.05) after the consultation than before. Heredity, stress and the environment were thought to be more decisive than diet, smoking and alcohol. 34 patients who seemed unlikely to have a genetic risk in the consultant's opinion thought heredity to be less relevant (P < 0.05) after the consultation than before. At the time of the survey, cancer patients accounted for at least half of the consultees attending oncogenetic clinics in France. They need to have the clinical specificities of their disease and its medical management explained. They attend mainly for their offspring's sake, whereas healthy clients attend for their own sake.