The authors present ten cases of eosinophil cystopathy and recall the very varied clinical signs of this disease: pollakiuria, haematuria, dysuria and the findings of complementary investigations: possible dilatation of the upper urinary tract, thickening of the bladder wall. Biopsy is essential and reveals lymphocyte and plasma cell infiltration and numerous eosinophils. The treatment administered was either immunosuppressants or dimethyl sulphoxide.