Background: Hyperoxalosis is a rare disease that originates from a defect in a liver enzyme and results in renal failure, if not diagnosed in time. Once end-stage renal disease is established, a transplant is the treatment of choice. But a kidney-only transplant can fail due to the mobilization of the excess oxalates in the tissue, and many authorities recommend a combined kidney-liver transplant. Case Presentation: We describe a case where the diagnosis of oxalosis was missed, resulting in renal transplant failure and excision of the graft. The diagnosis was made only on noting florid heterotopic calcification. A renal transplant was performed due to end-stage renal disease, but graft failure occurred and had to be excised due to recurrent oxalosis, again without diagnosis, despite imaging and graft biopsy. It was only when muscle calcification was noted for an unrelated indication that a diagnosis was made. The case highlights the importance of excluding all causes of nephrocalcinosis, including rare ones like oxalosis, in the management of chronic renal disease. Conclusion: We hope to alert the physician to consider primary hyperoxalosis as a differential diagnosis in renal failure patients with recurrent calcium oxalate renal stones and/or nephrocalcinosis.

Keywords: Hyper oxaluria, oxalosis, nephrocalcinosis, renal transplant failure, graft failure.