Background Erectile dysfunction is often associated with cardiac disease. The psychological fear of further cardiac complications during intercourse is a factor contributing to sexual dysfunction among cardiac patients. It is important for cardiologists to be aware of these issues. Methods We carried out a questionnaire survey among 145 Greek cardiologists’ knowledge and opinions concerning their patients’ sexual activity. The questionnaire was administered by trained nurses in the cardiologists’ place of work. Results Cardiologists tend to underestimate the scale of the problem and furthermore are not well informed about all aspects of it. This is especially true of younger members of the profession. Conclusions Greater awareness by physicians of this issue could enable them to contribute significantly to the quality of life of patients and their partners.