Twenty-five patients with rheumatoid arthritis (RA) and neutropenia, of whom 19 had a palpable spleen, were compared with 24 patients with uncomplicated RA, and 16 patients with RA and associated splenomegaly without neutropenia. Clinically patients with neutropenia had evidence of a more systemic disease as assessed by prevalence of rheumatoid nodules, weight loss, and recurrent infections. However, there was less evidence of active synovitis than in the other 2 groups. Marrow neutrophil reserve was studied by means of a hydrocortisone stimulation test and was found to be lower in all 3 groups than in normal persons but with most marked depletion in the neutropenic group. Removal of the spleen in some patients with neutropenia resulted in a significant increase in marrow neutrophil reserve. Circulating immune complexes as detected by anticomplementary activity and platelet aggregation tests were detected in 68% of the RA neutropenia group, 31% of the RA splenomegaly group, and 8% of the uncomplicated RA group. Our results show that, assessed both clinically and by the above tests, patients with neutropenia have a greater prevalence of abnormalities which may be directly related to their neutropenia. Patients with splenomegaly alone closely resemble patients with uncomplicated RA.