Abstract: As one of the most common urinary abnormalities, hematuria is one of early manifestations of various glomerular diseases in children. Beside kidney diseases, other diseases may also cause hematuria. Therefore proper assessments, diagnoses and treatments of hematuria have remained essential skills for pediatric nephrologists. For its definite diagnosis, there are standard procedures of qualitative assays, localization studies and cause determinations. The author proposed some personal suggestions on the definition, classification and diagnosis of hematuria. It also emphasized that isolated hematuria only refers to continuous microscopic hematuria while gross hematuria belongs to the category of hematuria and protein. For isolated continuous microscopic hematuria, thin basement membrane nephropathy is the most common cause. Instead of renal biopsy, gene detection is preferred for diagnosis.