Modern techniques that enable the molecular characterisation of cancerous tissue have lead to the development of new and more specific therapies. Trastuzumab (Herceptin), a monoclonal antibody drug for the treatment of breast cancer, is one such therapy. Now that trastuzumab is approved for use in the UK, this article will discuss the nursing management of its infusion, possible side effects, aftercare and the psychological needs of the patient being treated with this new drug.