The long term efficacy and tolerability of sulphasalazine (SASP) in the treatment of 21 patients with active classical or definite rheumatoid arthritis (RA) were examined and compared with the effects of penicillamine in a similarly active group of RA patients. Nineteen of the 21 patients treated with SASP improved during the first 6 months as shown by significant changes in the clinical and laboratory variables. Clinical improvement was maintained for the remainder of the year. Improvement in laboratory variables was maintained at 9 months but showed some deterioration at 1 year. Six patients went into remission by the ARA criteria, and 16 were able to continue the drug at the end of 1 year. In addition SASP had a steroid-sparing effect in 4 of the patients on systemic steroids. No potentially dangerous side effects were encountered by the end of the first year, although 5 patients were withdrawn. Dyspepsia, nausea and abdominal discomfort were the most common side-effects, although rashes (3) and macrocytosis (2) also occurred. Eighteen of the 21 patients treated with penicillamine improved during 9 months, although there was some deterioration at 1 year. Eight patients were withdrawn because of side-effects - thrombocytopenia (5), nephrotic syndrome (1) and proteinuria (2). This study suggests that SASP has a disease modifying action maintained over a year and associated with low toxicity. It is a useful addition to the small number of second-line drugs with a possibly different mode of action.