A total of 32 percutaneous renal biopsies were examined from patients with rheumatoid arthritis. The renal biopsies in these patients present a very heterogeneous picture; there were 9 cases of chronic interstitial nephritis and 4 cases of amyloidosis. In one patient whose renal biopsy showed glomerulitis, a muscle biopsy resulted in a diagnosis of polyarteritis nodosa. 11 biopsies showed a normal histology, and 6 showed arteriosclerosis of the small arteries. Finally, 1 patient showed so-called membranous glomerulonephritis; this may have been the coincidental presence of 2 diseases. We were unable to confirm the existence of a vascular rheumatoid lesion, as previously reported in the litterature. Employing a technique which permitted a quantitative evaluation of the nuclear distribution in the glomeruli, this distribution was examined in the biopsies from 28 patients with rheumatoid arthritis and in 11 patients with gallstones, but with normal renal function and normal blood pressure. The presence of a glomerular hypercellularity in rheumatoid arthritis, as has previously been claimed was not confirmed. It was likewise not possible to demonstrate local hypercellularity in the glomeruli of patients with rheumatoid arthritis and normal renal biopsies.