The authors discuss current pharmacological knowledge of D-Penicillamine (DP) in man and its possible mechanism in the treatment of rheumatoid polyarthritis. Dosage by liquid phase chromatography enables study of intestinal absorption, reduced by meals, the distribution made according to a 2 compartment model, urinary and faecal excretion. Metabolism occurs mainly by oxidation of free D-Penicillamine. 20 percent of the plasmatic DP, not bound to proteins, appears in the form of disulphides and free DP. The only known metabolite is S-methyl DP, produced in small amounts. The DP mechanism remains hypothetical. The authors discuss its effects on the metabolism of copper and zinc, dismutatic super-oxide activity, the radical thiol level, collagen metabolism, cartilaginous destruction, prostaglandin synthesis, polynuclear chemotaxis and the immuno-system.