Increasing numbers of medical practitioners and medical students are using online social and business-related networking websites such as Facebook, Doc2doc and LinkedIn. These rapidly evolving and growing social media have potential to promote public health by providing powerful instruments for communication and education. However, evidence is emerging from studies, legal cases, and media reports that the use of these new technologies is creating several ethical problems for medical practitioners as well as medical students. Improper online activities may harm not only individual reputations and careers, but also the medical profession as a whole, for example by breach of patient confidentiality,defamation of colleagues and employers, undisclosed conflict of interests that bias the medical practitioner’s medical advice, posting of advice/information without an evidence base, and infringement of copyright.