Since 1980 we have refined a procedure for renal needle biopsy with continuous ultrasonic guidance (USRNB) which facilitates control of the needle progression through the soft tissues to the lower pole of the kidney. The advantage of this method is evident in a selected population (major obesity, small kidneys). We compared this procedure to the conventional blind biopsy in a series of 32 nonselected patients. Tissue samples with more than 10 glomeruli were obtained in 87% of patients with 2.8 punctures using USRNB, the difference was significant when compared to a blind technique (56%, 4.0, respectively, p less than 0.05). USRNB has been performed in 108 patients with 2 failures due to a poor echographic contrast. Reasons why this procedure should be substituted for the blind technique include: (i) Less morbidity, (ii) improvement of the quality of renal tissue, (iii) better comfort for both patient and physician, and (iv) less technical restriction of the biopsy indication when compared to blind renal needle biopsy.