Purpose: The purpose of this study was to investigate nursing services of Oncology Advanced Practice Nurses(OAPNs) from the view point of structure and process. Methods: Roles and practices of OAPNs for cancer patients on chemotherapy were investigated by semi-structured interview and survey. Subjects were 14 OAPNs in 3 hospitals. Results: OAPNs had high level of education and certification than registered nurses. Most subjects of OAPNs were patients on chemotherapy and OAPNs used most of their time in education and expert nursing practice. 57.1% of OAPNs used delegated order. They were satisfied with their job in general, but satisfaction in communication with nurse manager or resident doctor was low. Conclusion: These results will be the concrete explanation for the nursing services of OAPNs. On the basis of theses results, more study about effects of OAPNs will be needed.