The potential advantage to patients with chronic rheumatic diseases of an effective, non-steroidal analgesic/anti-inflammatory drug which causes insignificant gastric bleeding was a decisive factor leading to the introduction of alclofenac. Short-term double-blind trials showed that alclofenac has analgesic/anti-inflammatory activities equivalent to phenylbutazone, indomethacin and aspirin, but superior to the fenemates and propionic acid derivatives. Long-term controlled studies, ranging from 5 months to 3-1/2 years and using reliable, objective measures revela, however, that patients with rheumatoid arthritis improve in functional status and graduate to less severe classes of disease activity, a phenomenon not observed with either indomethacin or aspirin administered to matched patients over the same periods of time. So far, clinical improvement on alclofenac has been matched only by treatment with gold, D-penicillamine and the immunosuppressive anti-proliferative drugs. This clinical improvement on alclofenac is reflected in haematological and serological indices, and research shows that alclofenac, like these other antirheumatoid drugs, has a pronounced effect upon the acute-phase protein response and the extent to which L-tryptophan is bound to plasma protein. The clinical data reviewed suggest that alclofenac represents an advance in the therapy of the rheumatic diseases.