A brownish discoloration of the bladder mucosa on cystoscopy and the histological findings in a bladder biopsy specimen of submucosal vascular basement membrane thickening, pigment or chronic inflammatory changes in the absence of infection were present in various combinations in all our patients with analgesic-associated nephropathy. None of these findings was present in a control group of patients with other established causes of renal function impairment. More objective diagnostic aids may lead to a greater awareness and earlier diagnosis of this preventable cause of chronic renal failure.