SUMMARYIn this study the value of undertaking routine blood and urine estimations was assessed in relation to achieving maximum efficacy and safety in chrysotherapy. It was found that a favourable response to gold was forthcoming in approximately two-thirds of patients and occurred irrespective of the patients' disease duration or severity, or the mean serum gold level or the mean urinary gold excretion, estimated immediately before the next gold injection was due. The presence of rheumatoid nodules and the patients' advancing age were associated with a less favourable clinical response to gold.Those patients who derived a marked benefit from chrysotherapy did so significantly earlier in their course than those who derived only moderate benefit.A frequent correlation was seen in individual patients between serum gold levels and urinary gold excretion. This was most marked in those patients showing a favourable response to gold.