Mononuclear cells (MNC) from rheumatoid synovial tissue and peripheral blood were tested for immune responses to various viral antigens, purified protein derivative (PPD) and Mycoplasma pneumonia by the indirect leucocyte migration inhibition test. MNC from the eleven rheumatoid synovial tissues tested had deficient leucocyte inhibitory factor production against all antigens tested for, and this was also the case in the peripheral blood of seven juvenile rheumatoid arthritis patients (JRA). In the peripheral blood of eight rheumatoid arthritis (RA) patients there was also generally low reactivity. However, significant differences in migration indexes were found with rubella viral antigen and with PPD at 5 μg/ml when zero‐hour and overnight incubations of the culture were compared. In contrast, MNC of peripheral blood of control donors had significant responses to PPD (19/19), mumps virus (7/11), rubella virus (10/19), cytomegalovirus (4/11), and herpes simplex type 1 virus (4/11) antigen after zero‐hour culture, and no differences was seen after overnight incubation. Copyright © 1979, Wiley Blackwell. All rights reserved