Cancer patients are showing increased interest in shared decision-making. Patients with haematological illnesses, however, express considerably less desire for shared decision-making as compared with other oncological patient groups. The goal of the current project was to identify the reasons for the lower desire for shared decision-making among patients with haematological illness. We conducted qualitative, semi-structured interviews with 11 haematological patients (39–70 years old) after the beginning of therapy concerning the course and evaluation of medical shared decision-making. The patients were often overwhelmed by the complexity of the illness and the therapy and did not want to assume any responsibility in medical decision-making. They reported a great deal of distress and very traditional paternalistic role expectations with regards to their health care providers, which limited the patients' ability to partake in the decision-making process. In contrast to the socio-cultural support for many other oncological diseases, haematological diseases are not as well supported, e.g. there is a lack of self-help materials, systematic provision of information and support groups for patients, which may be related to a lower empowerment of this patient population. Results show the limits of patient participation in the context of highly complicated medical conditions. In addition to already researched preferences of the physicians and patients for shared decision-making, future research should pay greater attention to the process and other variables relevant to this aspect of the doctor–patient relationship.