Today I want to talk about hematuria. Why? Today a patient asked me anxiously, “I found hematuria on my urinalysis and it’s been many times, it’s been treated for a long time and it’s always there, what should I do?” I asked her if it was occult blood or how many red blood cells she saw per high magnification under the microscope, and she said it was occult blood, which is usually 0 or 1 or 2 under the microscope. I told her then there was no need to be nervous, that what we usually call hematuria actually means that the microscopic red blood cell count exceeds 3 per high magnification, and that occult blood is affected by the test and cannot be used as a basis for diagnosing hematuria. In addition, if the urinalysis does reveal more than 3 red blood cells per high-powered microscope, it is necessary to check the urine phase difference (or urine sediment), and if the variant red blood cells exceed 60%, it means that the glomerulus is indeed damaged, and to clarify what the disease is, the most accurate method is to do a kidney puncture biopsy. Otherwise, extra-renal problems, such as gynecological, surgical, tuberculosis, tumor, etc. should be considered. Here, I would like to say that we should clarify the definition of “hematuria” and not be nervous when we see positive occult blood, but we mainly look at the number of red blood cells under the microscope.