In a series of 96 patients with membranous glomerulonephritis (MGN) there were 14 who had concomitant rheumatoid arthritis. Ten of these had been treated with gold or D-penicillamine; in four patients neither of these drugs could have been responsible for the MGN. One of them received intrasynovial osmium tetroxide two months before the clinical onset of MGN. Three of the patients had positive rheumatoid factor. HLA-type was examined in three patients and all showed B27 antigen but not DR3. No patient developed signs of systemic lupus erythematosus during the follow-up (mean 5.9 years). In two patients MGN persisted as judged from urinary abnormalities, one patient recovered after a relapse period and one developed secondary amyloidosis.