Simple hematuria refers to the condition in which the number of red blood cells in urine exceeds the normal level without clear systemic and urinary diseases and their symptoms (such as edema, hypertension, renal dysfunction, etc.). Simple hematuria is a symptomatic diagnosis. After excluding various diseases that can cause hematuria, asymptomatic, isolated hematuria (without proteinuria) with unclear etiology is considered "simple hematuria". In the draft classification of kidney disease drawn up by the Pediatric Nephrology Research Collaborative Group of my country in 1979, it was called "asymptomatic hematuria", and it was revised to "simple hematuria" in 1981. This name is similar in meaning to the so-called "isolated hematuria" internationally.