Hematuria is a common clinical, especially urological, symptom that worries and scares patients! However, there are a few patients who ignore it. Unless hematuria causes retention of blood clots in the bladder, renal colic due to discharge of blood clots, or anemia, the patient needs to be seen in the emergency department, but in other cases, hematuria is seen in the general outpatient clinic. Blood in urine can be seen by the naked eye and is called visual hematuria; microscopic examination reveals ≥3 red blood cells/high magnification field and is called microscopic hematuria; hematuria can also be detected by urine test strips. The urine test strip test only tests for hemoglobin and not intact red blood cells. Only 5 ml of blood per liter of urine can be observed by the naked eye. Screening tools for causes of hematuria: urine culture, cytology, urological ultrasound, flexible cystoscopy, intravenous urography, CT and MRI, etc. By these means, the cause of hematuria cannot be found in about 50% of patients with visual hematuria; the cause of hematuria cannot be found in about 60% to 70% of patients with microscopic hematuria. The causes of hematuria are divided into nephrogenic (medical) and urological (surgical) causes. The medical causes include glomerular and non-glomerular factors (e.g., hematologic disease, interstitial nephritis, and renal vascular disease). Glomerular-derived hematuria causes red blood cell deformation, red blood cell tubularity, and proteinuria. Non-glomerular-derived hematuria has round red blood cells, no erythrocyte tubular pattern, and no proteinuria. Surgical non-glomerular factors causing hematuria include renal tumors, uroepithelial tumors (bladder, ureter and renal collecting system), prostate cancer, prostate enlargement, trauma, stones and urinary tract infections. Hematuria caused by these factors usually has round red blood cells, no proteinuria and tubular pattern on laboratory tests.