(1) Observations are reported on two independent semiquantitative histologic analyses of 57 renal biopsy and autopsy specimens from patients with SLE. The analyses were each made by two observers and were done six years apart. (2)The technique was shown to be reproducible. Differences of more than one grade on a scale 0 to 4+ were uncommon. When there were differences they were consistently in the same direction, and the major differences found could be explained by improvements in technique and understanding of the microscopic anatomy and pathology of the kidney which took place in the intervening six years. (3) Semiquantitative histologic analysis of renal biopsy specimens is a method which can be used to study with confidence sequential histologic changes, and structural-functional interrelationships.