PURPOSE: The purpose of the study was to explore and describe the job experiences of oncology nurse specialists. METHODS: Nine oncology nurse specialists participated in the study. Data were collected through in-depth unstructured interviews with individual participants from February to June, 2014. Theoretical sampling was used to the point of theoretical saturation. Data were analyzed using Corbin and Strauss's grounded theory method. RESULTS: From open coding, 98 concepts, 24 sub-categories, and 11 categories were identified. Analysis revealed that the core category of the job experiences of oncology nurse specialists was 'tightrope walking of professionalism without safeguards', consisting of four phases: Enthusiastic beginning, conflict, exertion, and internalization. To manage the 'tightrope walking of professionalism without safeguards', participants utilized various action/interactional strategies such as 'keeping the balance point' and 'taking a step forward.' As a result, participants experienced falling into a habitual routine and professional self-actualization. CONCLUSION: In-depth understanding of the job experiences of oncology nurse specialists will guide hospital administrators to promote effective interventions and policies to better support Korean oncology nurse specialists.