The effect of hematuria on IgA nephropathy (IgAN) remains unclear and the treatment of IgA nephropathy with severe hematuria is controversial. Eighty-eight patients with IgA nephropathy were selected and required: 24-hour urine protein quantification <0.5g at the time of nephrostomy, no treatment with glucocorticoids or immunosuppressive drugs, and no tonsillectomy. Patients were divided into two groups: 1, low urine red blood cell count group (L-RBC group) (U-RBC <20< span> units/HPF, n=48); 2, high urine red blood cell count group (H-RBC group) (U-RB ≥20 units/HPF, n=40). The analysis was performed in terms of clinical and histological studies, renal survival and risk factors for the progression of kidney disease. Male morbidity and blood pressure were significantly higher in the L-RBC group than in the H-RBC group. Mean proteinuria, estimated glomerular filtration rate (eGFR) and histological studies elucidated in the Oxford staging were similar between the two groups. The median 24-hour urine protein quantification remained less than 0.5 g or less than 0.5 g/g in both groups during the 5-year period after the diagnosis of IgA nephropathy by renal biopsy without any intensive treatment, and the median U-RBC decreased to less than 10/HPF in both groups. 15-year kidney survival estimated by the Kaplan-Meier method was 100 percent, while the L-RBC group decreased to 83.4 percent, but there was no significant difference between the two groups. Inhibition of the renin-angiotensin system (RAS inhibitor) reduced the risk of disease progression by Cox regression analysis (hazard ratio: 0.14, P = 0.027). In renal biopsy-confirmed IgA nephropathy, severe hematuria improved spontaneously, even without any intensive treatment. Hematuria did not have any negative impact on IgA nephropathy with mild proteinuria. The prognosis for hematuria is relatively good, and treatment with RAS inhibitors may stop the progression of kidney disease.