Higher than normal amounts (p less than 0.001) of manganese were found in granulocytes isolated from patients with rheumatoid arthritis, other inflammatory arthritides, and scleroderma, while erythrocytes and platelets contained normal amounts of manganese. The cause of manganese accumulation is not known but evidently is linked to the intensity of the inflammatory process since significant positive correlations (p less than 0.001) were seen between erythrocyte sedimentation rate or serum haptoglobin and granulocyte manganese. During corticosteroid therapy granulocyte manganese started to return to normal levels but the relative changes were modest. Strong positive correlations (p less than 0.001) were found between granulocyte manganese and granulocyte stores of calcium and iron, suggesting a close relationship in the cellular regulation of these elements in chronic inflammatory conditions.