A decreased production of interferon-gamma (IFN-gamma) and interleukin-2 (IL-2) upon in vitro stimulation by phytohemagglutinin (PHA) peripheral blood leucocyte in active rheumatoid arthritis (RA) patients has been described as an important immunological abnormality in this disease. However, the molecular level at which this defect might occur has not been fully documented. We have investigated the kinetics of IFN-gamma, interleukin-2 receptor (IL-2 R), and interleukin-1 beta (IL-1 beta) messenger RNA (mRNA) expression in RA patients (n = 9) and normal controls (n = 5) after PHA leucocyte activation. We demonstrate here a significantly decreased expression of IFN-gamma mRNA in RA patients without modification of its kinetics associated with a similar IL-1 beta mRNA expression.