Background: The rising incidence of cancer in Switzerland, coupled with an increasing frequency of oncology drug shortages, represents a growing challenge for healthcare systems. Shortages may disrupt continuity of cancer care, increase healthcare providers’ workload and treatment costs. Objective: To describe the frequency and duration of oncology drug shortage events at Geneva University Hospitals (HUG) and at the national level in Switzerland from 2019 to 2023. Methods: We conducted a retrospective descriptive analysis using (i) a prospectively maintained internal pharmacy record at a Swiss tertiary care hospital (HUG) and (ii) national shortage notifications from the Swiss Federal Office of Public Health (FOPH) and the Federal Office for National Economic Supply (FONES). Shortage events affecting anticancer agents were extracted and summarised descriptively by frequency and duration. Results: At the HUG, 29 shortage events were recorded, affecting 11 cytotoxic agents (median duration 62 days). Of these events, 43% lasted 1–3 months and 21% lasted >6 months. Nationally, 88 shortage events were reported, affecting 14 cytotoxic agents (median duration 70 days). The most frequently affected agents were methotrexate, epirubicin, gemcitabine, and doxorubicin. No shortages were reported for immune checkpoint inhibitors, monoclonal antibodies, or tyrosine kinase inhibitors. At the national level, 38% of events lasted 1–3 months and 27% lasted >6 months. Conclusion: Even in a high-income country with relatively high drug prices, oncology drug shortages occur and predominantly affect older but essential cytotoxic agents. Although therapeutic alternatives are often available, prolonged unavailability increases clinical and operational complexity. Strengthening supply-chain resilience and improving coordination between hospital-level and federal reporting systems are key to mitigating future shortages and safeguarding patient care.