Ingestion of Clitocybe amoenolens, a mushroom collected in Savoie (France), induced erythermalgia in 5 patients. To assess C. amoenolens toxicity, increasing doses were given randomly to 4 rats corresponding to 1 to 25 fold the dose eaten by the most severely poisoned patient. The 2 rats receiving the highest doses had loss of bodyweight, locomotor disability and erythema of the toes. Examination of sciatic nerves showed decreased axon density and neuronal fiber degeneration. Oral administration of C. amoenolens to rats led to lesions that might be explained by the presence of acromelic acid A, a kainate analogue.