This chapter provides an in-depth case study of a nurse-led clinic. It focuses on the development, implementation, ongoing evaluation and latest update of a nurse-led pathway for Human Epidermal Growth Factor Receptor 2 (HER2) positive breast cancer patients receiving Trastuzumab (Herceptin). Although primary focus was on early-stage disease, the pathway also includes some patients with metastatic disease. The various stages of the pathway development are explained and supported by relevant evidence from the appropriate time period. Within the cancer setting, there has always been a focus on delivering efficient and patient centred care by utilising clinical guidelines/pathways. The professionals were dependant on each other to make the Trastuzumab-pathway work effectively and were all accountable for its implementation and ultimate success. The National Health Service Modernisation Agency and National Institute of Clinical Excellence highlighted the importance of conducting a baseline assessment of what impact the planned changes may have on the existing service and any current shortfalls which would need addressing.