An immunological evaluation was performed before therapy and every four months during the first year of treatment with auranofin in 6 children with juvenile chronic arthritis. The immunological tests included: IgG, IgA, IgM, IgE and "natural" antibody serum levels, CH50 of the classical and alternative complement pathways, PWM-induced IgM production in vitro, and polymorphonuclear neutrophil functions. A reduction of the in vitro IgM synthesis and in the CH50 of the classical pathway of complement, and a normalization of impaired chemotaxis, occurred in patients who presented a clinically significant improvement during auranofin treatment.