Perhaps the most important conclusion is that much remains to be learnt about how to use penicillamine in clinical practice. The results described have been obtained by observing groups of patients on various fixed schedules of dosage. There may be a case for using a more flexible system but this makes comparisons difficult and at this stage predetermined fixed schedules have been preferred. A total daily dose of 1500 mg is clearly excessive and probably unnecessary. There is some suggestion that administration between meals produces better and perhaps more predictable absorption. If used in this way the total daily dose should be lower than the one found most suitable when the drug is given with food. Experience to date favours a daily total of 375 mg given between meals. The late onset of some adverse reactions in patients on low doses suggest that the total cumulative dose may be relevant and that some toxic reactions are liable to occur when a certain total intake has been reached. No mention has been made in this survey of comparisons with other drugs. The main task has been seen to be the exploration of various dosage schedules in the hope of finding an effective dose which does not produce a high incidence of adverse effect. Only when this information has been obtained will it once again become relevant to test the drug under control conditions either against an inactive placebo or some other anti-rheumatoid drug.