The delivery of cancer care in Ontario is facing unprecedented challenges. Shortages in nursing, as in all professional disciplines, are having an impact on the delivery of cancer care. Oncology nurses have a major role to play in the delivery of optimum cancer care. Oncology nursing, when adequately defined and supported, can benefit the cancer delivery system, patients, and families. A primary nursing model is seen as being key to the delivery of optimum cancer care. Primary nursing as a philosophy facilitates continuity of care, coordination of a patient's care plan, and a meaningful ongoing relationship with the patient and his/her family. Primary nursing, when delivered in the collaboration of a nurse-physician team, allows for medical resources to be used appropriately. Defined roles enable nurses to manage patients within their scope of practice in collaboration with physicians. Enacting other nursing roles, such as nurse practitioners and advanced practice nurses, can also enable the health care system to manage a broader number of patients with more complex needs. This article presents a position paper originally written as the basis for an advocacy and education initiative in Ontario. It is shared in anticipation that the work may be useful to oncology nurses in other jurisdictions in their efforts to advance oncology nursing and improvement of patient care.