Although daily ingestion of high-dose vitamin C is generally regarded as largely innocuous, fatal nephrotoxicity can occur in some rare circumstances. We report a case where the patient, who chose to forgo any advanced conventional medical intervention (dialysis and mechanical ventilation), had failed to disclose his use of high-dose vitamin C and subsequently died. Intra-renal oxalate crystal deposition was demonstrated at autopsy. Directed enquiry with the family then revealed his high-dose vitamin C usage. Even though fully-informed discussion was limited by incomplete prospective disclosure, it remains the prerogative of any competent patient to decline any treatment, including those that may be considered life-saving.