A new treatment form has emerged that merges cognitive behaviour therapy with the Internet. By delivering treatment components, mainly in the form of texts presented via web pages, and provide ongoing support using e-mail promising outcomes can be achieved. The literature on this novel form of treatment has grown rapidly over recent years with several controlled trials in the field of anxiety disorders, mood disorders and behavioural medicine. For some of the conditions for which Internet-delivered CBT has been tested, independent replications have shown large effect sizes, for example in the treatment of social anxiety disorder. In some studies, Internet-delivered treatment can achieve similar outcomes as in face-to-face CBT, but the literature thus far is restricted mainly to efficacy trials. This article provides a brief summary of the evidence, comments on the role of the therapist and for which patient and therapist this is suitable. Areas of future research and exploration are identified.