Introduction: Non-gestational choriocarcinoma (NGCC) is an extremely rare cancer. We report a case presenting in extremis. Case Report: A 39-year-old woman presented with type 1 respiratory failure with a 1-month history of breathlessness. Computed tomography (CT) revealed widespread metastatic disease involving the lungs, liver, pancreas, and breast. Serum β-human chorionic gonadotropin was markedly raised. Over 72 h, she deteriorated and was started on high-flow nasal cannula to facilitate discussions and for comfort. Histology from a breast biopsy suggested a choriocarcinoma, and she was commenced on etoposide and cisplatin. Unfortunately she continued to deteriorate and died on day 11 of admission. Molecular genotyping received post-mortem confirmed non-gestational choriocarcinomatous differentiation within a high-grade tumour. Discussion: NGCC carries a worse prognosis compared with gestational choriocarcinoma and is historically less chemosensitive. However, differentiation between these two diagnoses is challenging due to a lack of immuno-histochemical differences. The NGCC in this case was likely to have originated in the lung due to a 12-cm mass in the lingula, and extensive emphysema on CT. Primary pulmonary choriocarcinoma has a rapidly fatal course in the majority of patients. Conclusion: This is the only case to our knowledge of NGCC presenting in extremis, where an accurate diagnosis was not achieved pre-mortem. This also demonstrates the merit of non-invasive ventilation within palliation to facilitate communication and comfort.