Mass media is an important forum for the interaction between science and the general public, and media participation has been recognized by the Finnish Medical Association as a duty of physicians. Physicians are an important source of health information for journalists and their perceptions of reliability may influence which medias they are willing to collaborate with. In this study, Finnish physicians were asked to evaluate and define the characteristics of reliability for health information in the media. The survey was filled out by 266 physicians, who estimated that the most reliable mass media sources of health information are scientific publications, medical associations, universities, The Finnish National Institute for Health and Welfare, and other non-profit research centres. The lowest reliability scores were given to online discussion forums, entities representing complementary, and alternative medicine and individual patients. Female physicians and older physicians gave most health information sources higher scores than men or younger respondents. These results highlight a potential conflict between the need to translate scientific language to a form understandable to the general public, and a demand placed by physicians on journalism to be as scientifically accurate and precise as possible. In order to best convey their message to the general public, the professional skills of journalists should be utilised by physicians to overcome this issue.