In evaluating a new procedure such as needle biopsy of the kidney, it is important to know (1) its ease of performance, (2) its morbidity and mortality, and (3) its clinical usefulness. The first two points have been covered fairly well previously by us and by others.* In order to assess the last point we have chosen 100 successful renal biopsies and compared the clinical and pathological impressions. These 100 biopsies are taken from a total of 169 biopsy attempts, of which 131 yielded renal tissue. In 31 patients, however, the results were discarded from the study because the biopsies were unsatisfactory or because they were repeat biopsies on the same patients.
Kidney biopsy specimens were obtained by means of a Turkel needle, formalin fixed, paraffin embedded, sectioned, and stained with hematoxylin and eosin and whatever other stains were necessary.5 Such sections measured 5 to 20 mm. in