Microscopic hematuria is a common problem that may affect up to 13 per cent of the population. The number of RBCs identified in the urine sediment is dependent, in part, upon the technique used in performing the urinalysis. The exact number of RBCs normally excreted into the urine has been difficult to establish. However, three to eight RBCs per HPF would be accepted by most investigators as an acceptable dividing point between normal and abnormal hematuria. Although the prevalence of microscopic hematuria in the general population is high, the number of patients who have serious urologic disease is low. Many diagnostic algorithms are available for evaluating these patients, but at the present time there is still uncertainty regarding how extensive the evaluation should be for patients with asymptomatic microscopic hematuria.