This study aimed to investigate experiences of verbal and written information about sex and relationships among men and women treated with hematopoietic stem cell transplantation. The study also aimed to investigate the demand for information and assessment of the quality of written patient information material entitled "Sex and relationships in the treatment of blood diseases." Few studies exist that shed any light on the demand for information about sex and relationships on the part of patients with hematological diseases before, during, and after their treatment. A total of 216 patients undergoing treatment for malignant blood diseases between 2000 and 2010 participated in this study. Patients' experiences of information about sex and relationships, and their opinions about the written patient information, were assessed using a questionnaire created specifically for this study. Most patients (81 %) had not received information about sex and relationships from a healthcare professional. Almost 90 % of men felt that verbal information was important, compared with 82 % of women. The majority also held that written information was important. These results indicate that patients, regardless of gender, age, and treatment, consider oral and written information about sex and relationships to be important and that the healthcare system should provide the information. The written patient information was considered to play an important role in creating an opening for a conversation about a sensitive topic such as sexuality, and also as a source of reference and support for the patient and his/her partner.