BACKGROUND: Up to 50 % of all cancer patients require psychosocial support during the course of their disease. However, only a proportion of these patients make use of the existing services. This is partly because patients are unaware that psychosocial support services are available to them. We investigated whether systematically providing printed information concerning psychosocial support can increase the knowledge and usage of these services, as well as health-related self-efficacy. MATERIALS AND METHODS: In a controlled trial, 108 breast cancer patients were assigned alternately to either an intervention- or a control group. At two predefined time points before and during radiotherapy, patients in the intervention group received correspondence informing them about psychosocial services (psycho-oncology, clinical social work and the Cancer Information Service).The control group received no systematic information. Using a standardized questionnaire, all patients were subsequently questioned about their knowledge of psychosocial support services, their perceived self-efficacy and their use of psychosocial support services. RESULTS: We found that systematic provision of information had a positive effect on the knowledge of psychosocial support services (p = 0.042; d = 0.45) and self-efficacy (p = 0.047; d = 0.42). However, no increase in the actual usage of these services was observed (p = 0.661; d = 0.10). CONCLUSION: The systematic provision of information in the form of written correspondence can easily be implemented into clinical routine and is an effective way to increase cancer patients' knowledge of psychosocial support services. Furthermore, providing information about the services had a positive impact on patients' perceived self-efficacy. However, simply making this information available did not increase the usage of psychosocial support services.