This study was performed in order to characterize whether T cells from rheumatoid synovial inflammation belong to the Th1‐ or Th2‐like functional subsets. Cytokine production was studied in 26 CD4⁺αβ⁺ and 2 CD8⁺αβ T‐cell clones from the synovial fluid, the synovial membrane and peripheral blood of 5 patients. Fifteen of the CD4⁺ clones were raised against various mycobacterial antigens and 11 CD4⁺ clones and 2 CD8⁺ clones were raised unspecifically using PHA and/or IL‐2. The specificities of these clones are not known. In the mycobacterial antigen‐specific group, all CD4⁺’αβ T‐cell clones produced IFN‐γ at high levels, while the production of IL‐4 was generally absent or low (< 1 ng/ml), consistent with a Thl‐like profile. Some of these clones, however, also produced various amounts of IL‐10 which has been regarded as a Th2 product but can be produced also in lower amounts by Thi cells. One HSP‐65‐specific clone produced levels of IL‐4 and IL‐10 in the same order as that of IFN‐γ, thus appearing to be Th0‐like. Among the 11 unspecific CD4⁺ clones, 7 showed a Thl‐like pattern but with lower levels of IFN‐γ than the antigen‐specific clones. However, three clones did not produce any IFN‐γ activity but produced IL‐4 and one of them also produced distinct amounts of IL‐10, compatible with a Th2‐like pattern. In addition, one of the clones also showed an almost equally strong IFN‐γ and IL‐4 production, thus most likely representing a Th0‐like clone.