Remittive drugs for rheumatoid arthritis (RA), such as hydroxychloroquine (Pickup, Dixon & Bird, 1980), aurothiomalate and D-penicillamine (Evans, 1977; Haataja, Nissila & Ruutsalo, 1978; Hall, 1980) levamisole (Hall & Gillan, 1979), and cyclophosphamide (Gutlan, 1979; Pickup et al., 1980) have been found to induce inRA patients, during long-term treatment, a significant increase in serum sulphydryl (SH) total concentrations up to a return of these towards the normal range, accompanied by clinical improvement.

Low dose haloperidol, like the above drugs, has been shown to be able to induce in RA patients during 6 months of treatment a progressive and signi-ficant increase in serum protein SH levels, and a significant decrease in technetium index (Tc-index), erythrocyte sedimentation rate (ESR), and joint count (Grimaldi, 1980a; Grimaldi& Bergonzi, 1980). The studies described herein were designed to probe whether long-term haloperidol treatment induces a sustained increase in serum SH levels, and to evaluate whether the changes in serum SHi concentrations correlate with the changes in objective indices of the disease activity, suchas Tc-index, ESR, and joint count.