This paper examines ethical implications in the use of social media by professional communicators. Using its research into the experiences of New Zealand practitioners, it identifies major ethical challenges for the profession. It also illustrates how social media intensify ethical issues that public relations has struggled with in the off-line world. At the same time, it shows how social media open opportunities for increasing practitioner influence on organisational ethics in ways long desired by traditional practitioners and recently advocated by public relations academics. It concludes that, despite enabling a lack of transparency and easier deception, social media can help public relations both improve ethical communication with stakeholders, and gain a greater ethical leadership role.