To identify cancer patient and relatives beliefs, information needs, information-seeking behavior and information sources about cancer and treatment. This research was conducted at two hospitals of a university. Data was collected via questionnaires and the Turkish version of the Miller Behavioral Style Scale (MBSS) to assess information-seeking behavior. The sample included 82 patients and 54 relatives. Patients were receiving treatment mostly for breast, gynecologic, lung cancer and leukemia/lymphoma. All of them indicated that they want to be informed by a doctor about their diagnosis and treatment first. Other information sources were internet, media and nurses. The majority of the patients and half of their relatives agreed that “cancer is curable and preventable disease”. Only 2.5% of patients agreed with the statement “I don’t want to get information about disease which disturbs me”. According the data obtained from MBSS; the mean patients MBSS score (6.41±3.2) was higher than their relatives (5.46±3.1). Respondents with higher education and younger age indicated more information-seeking behavior. Patients and their relatives differ in some of their information-seeking behavior. Patients beliefs and their strategies for coping with their illness can constrain their wish for information and their efforts to obtain it. Healthcare professionals need to assess and be sensitive to the information-seeking behavior of cancer patients and their relatives.