The aim of this study was to investigate whether (99m)technetium-labelled polyclonal human immunoglobulin G (99mTc-IgG) scintigraphy reflects synovial inflammation in patients with rheumatoid arthritis (RA). We evaluated 29 patients with RA for this reason and found a highly significant correlation between total scintigraphic scores and total tenderness scores (r = 0.781, P < 0.001). A significant correlation was also found between 99mTc-IgG scintigraphic scores and tenderness in all joints other than the shoulders. The 99mTc-IgG scintigraphy had a sensitivity of 69% and specificity of 88% in cases with tenderness and 72% and 81%, respectively, in cases with swelling. Total scintigraphic scores were correlated with serum levels of C-reactive protein (r = 0.401, P < 0.05) but not with erythrocyte sedimentation rate (r = 0.149, P > 0.05). The correlation between disease activity scores and total scintigraphic scores was also found to be significant (r = 0.812, P < 0.001). We suggest that 99mTc-IgG scintigraphy is a reliable and objective method in detecting synovial activity and can be appropriate for observing disease prognosis in clinical trials with RA.