99Tcm-polyclonal human immunoglobulin G (HIG) scintigraphy was used to detect active joint inflammation and to obtain ratios of joint uptake in noninvolved and inflammatory joints. Imaging was performed at 4 and 24 h in 16 patients with rheumatoid arthritis (RA) and 16 with degenerative joint disease (control group). All joints (total of 1344) were scored for pain, swelling and visual analysis of uptake in both scans. Joint to background (J:B) ratios were also calculated. Clinical and visual scores correlated in both scans (r = 0.7, P < 0.01). In RA patients, 246 joints were clinically involved. Visual analysis of scans detected 213 (87%) of them at 4 h and 196 (80%) at 24 h. Joints with no pain or swelling showed significantly higher J:B ratios than the control group and lower ratios than joints clinically involved. In the control group, statistically significant differences in J:B ratios between the various joints were found, so it was necessary to establish a normal range for every joint. J:B ratios were significantly higher at 4 h than at 24 h in both groups of patients. 99Tcm-HIG scintigraphy allows detection and measurement of joint inflammation. Scans performed at 4 h are preferable to scans at 24 h. Quantitative analysis can measure more objectively the degree of activity and could be useful in the management of these patients.