Purpose: Patients’or lay theories about the origin and nature of a disease are part of the complex of coping strategies. Lay theories can consist of etiologic considerations as well as beliefs about possibilities of influencing the disease. They can lead to expectations or result in reservations concerning a particular form of treatment. The discrepancy between the patient’s and the doctor’s causal attributions is considered to be one of the main causes of non-compliance. Material and Methods: Between October 2001 and February 2004 we carried out a questionnaire study in 100 patients suffering from ovarian cancer. By means of semi-structured interviews we investigated the patient’s causal attributions concerning the genesis of her illness. We asked the patient to spontaneously give us a theory as well as to choose from pre-defined factors. Results: Only 4%of the patients declared that they had never considered the question of the disease’s cause. 96%of the patients expressed lay theories with the following distribution: stress at home 55%, stress at work 36%, genetics 34%, hormones 29%, genital infections 20%, nutrition 19%, environmental pollution 12%, nicotine 9%. Spontaneously expressed theories were for example “radioactivity”, “mistreatment”, “punishment”, “poisoned food”, “surgery for inguinal hernia”, “falling”, and “homesickness”. Conclusions: The results show that the majority of patients have a great interest in clarifying the etiology of their illness. Lay theories can be complex and absolutely at variance with science. As lay theories have an impact on coping and compliance, and might influence treatment, doctors need to discuss these actively and as early as possible. Purpose: Patients’or lay theories about the origin and nature of a disease are part of the complex of coping strategies. Lay theories can consist of etiologic considerations as well as beliefs about possibilities of influencing the disease. They can lead to expectations or result in The discrepancy between the patient’s and the doctor’s causal attributions is considered to be one of the primary causes of non-compliance. Material and Methods: Between October 2001 and February 2004 we carried out a questionnaire study in 100 patients suffering from ovarian cancer. By means of semi-structured interviews we investigated the patient’s causal attributions concerning the genesis of her illness. We asked the patient to spontaneously give us a theory as well as to choose from pre-defined factors. Results: Only 4% of the patients declared that they had never considered the question of the disease’s cause. 96% of the patients expressed lay theori es with the following distribution: stress at home 55%, stress at work 36%, genetics 34%, hormones 29%, genital infections 20%, nutrition 19%, environmental pollution 12%, nicotine 9%. “activity ”,“ mistreatment ”,“ punishment ”,“ poisoned food ”,“ surgery for inguinal hernia ”,“ falling ”, and“ homesickness ”. Conclusions: The results show that the majority of patients have a great interest in clarifying the Lay theories can be complex and absolutely at variance with science. As lay theories have an impact on coping and compliance, and might influence treatment, doctors need to discuss these actively and as early as possible.