BACKGROUND Ingestion of certain Cortinarius species may lead to renal failure. In the Netherlands, this type of poisoning has not been previously described. METHODS A 58-year-old female presented with headache, vomiting and oliguria, preceded by a few days of burning, painful thirst and malaise. She had acute and irreversible renal failure of unknown cause. History revealed that two days before the onset of her symptoms, she had eaten a ragout prepared with mushrooms that were picked in a forest. A renal biopsy demonstrated interstitial nephritis with proximal tubular necrosis. In the leftovers of the ragout two fragments of Cortinarius mushroom, probably belonging to the complex of Cortinarius cinnamomeus (cinnamon webcap), were found. First signs and symptoms, and the course are compatible with those described in the literature on Cortinarius poisoning. Despite haemodialysis and administration of acetylcysteine and glucocorticoids, her renal function did not recover. CONCLUSIONS This case is the first description of mushroom poisoning by a species of the genus Cortinarius in the Netherlands.