[Difficult diagnosis in a case of hematuria (Berger's disease)].

A seven years old boy presented with gross hematuria associated with clots and transitory renal insufficiency. The urinary sediment showed only monomorphic red blood cells. Subsequently urinary sediment completely modified: namely only dysmorphic red blood cells and hyaline granular casts were found and within a week renal function become normal. The clinical diagnosis of Berger's disease was possible only with renal biopsy.