A clinical statistical survey was performed on 355 patients with asymptomatic microscopic haematuria. Urologic lesions were detected in 19.4% of the patients. Urologic lesions requiring surgical treatment were found in only two patients with bladder carcinoma and with renal calculus. With the exception of glomerulonephritis, the proportion of those over 40 years who had urologic lesions was higher. It is suggested that an initial evaluation based on excretory urography, cystoscopy and ultrasonography is more important for patients over 40 years.