Serum gold levels were monitored in 66 children with juvenile rheumatoid arthritis, treated with different i.m. dosage schedules of sodium aurothiomalate (Myocrisin, Pharma Rhodia). The ages of the children varied from 1 to 15 years. Gold serum levels in children were related to the dose of Myocrisin calculated per kg of body weight or per square metre of body surface area. The results of our study indicate that in order to achieve a peak serum level at about 500--600 microgram/100 ml (25--30 micromol/l) with weekly injections, the dose of Myocrisin should be about 0.7 mg/kg, or 20 mg/m2. In order to avoid excessively high gold serum concentrations, the maximum single dose should not exceed 27 mg/m2 of body surface area.