This article summarises the authors' experience and the data of the literature concerning Tiopronine, a drug with a thiol function like D-penicillamine, in the treatment of rheumatoid arthritis. Two controlled trials versus placebo and two controlled trials versus D-penicillamine demonstrated the effectiveness of treatment and the identical action of 1 g of Tiopronine and 600 mg of D-penicillamine. The side effects of Tiopronine are very similar to those of D-penicillamine: essentially rash, toxiderma, aguestia, proteinuria, which resolve when treatment is stopped. Patients with a past history of side effects with D-penicillamine have an increased risk of developing side effects with Tiopronine, but this risk is not systematic, which constitutes the principal value of this drug.