The use of social media in medicine has rapidly increased. Social networks are used by clinicians for many purposes, including clinical case discussions, professional networking, advertising their practice, and patient education. Researchers are using social media for recruitment and dissemination of research, and as a source of data. Patients are also using social media as a source of information on health conditions, although there is a significant amount of misinformation. In this lecture, we will discuss the pros and cons of social media use by clinicians, researchers and patients.