Rheumatoid arthritis is a chronic polyarthritis in which active inflamed joints coexist with joints in remission. We performed bone scans (99mTc-DPD) and 99mTc human polyclonal immunoglobulin G scans (99mTc-IgG) in 18 patients with rheumatoid arthritis to assess the uptake in actively inflamed joints and in joints in which remission after inflammation had occurred. A quantitative analysis of tracer uptake in each joint was performed on both scans. In 123 joints without current active inflammation, an increased 99mTc-DPD uptake was observed (2.31 +/- 1.27), whereas no 99mTc-IgG uptake was noted (1.18 +/- 0.32). Some 78 joints with mild pain or swelling exhibited increased 99mTc-DPD uptake (2.48 +/- 1.14) and increased 99mTc-IgG uptake (1.76 +/- 0.50; P less than 0.001), while 21 joints with moderate to severe pain or swelling exhibited increased 99mTc-DPD uptake (2.39 +/- 0.93) and increased 99mTc-IgG uptake (1.79 +/- 0.51; P less than 0.001). In conclusion, 99mTc-IgG scans distinguish between joints with and without active inflammation in chronic rheumatoid arthritis, whereas bone scans do not. Thus, 99mTc-IgG scans may be useful in identifying joints with current active inflammation in rheumatoid arthritis.