A critical component of cancer care, rarely addressed in the published literature, is an expected competency in oncology nursing education. The present text describes an effort to develop cancer-nursing competencies in Iran and the process of the needs assessment.A 3-phase, mixed-method approach for needs assessment was used, incorporating modified Delphi technique, literature review, interviews, and an expert panel. Different stakeholders, consisting of nurses, faculty members in fields related to oncology nursing education, and patients and their families, participated in different phases of the study. Data were analyzed using manual content analysis.In the present study, totally 123 sub-competencies were identified under holistic physical healthcare for patients, psychological and social care, spiritual care, palliative care, ability to prevent at three levels, teamwork and inter-professional competencies, management and leadership competencies, ability to conduct research and evidence-based nursing, supportive care, communication skills, professionalism, provision of education and counselling to patients and their families, and reasoning, problem solving, and critical thinking skills, respectively.An updated and applicable list of competencies was extracted, which can be used to design and develop educational programs, which seek to train qualified oncology nurses for an effective nursing care.