• Data are presented on 248 initial mobilization tests performed in an ambulatory setting over an 11-year period. Results demonstrate that there is no single, consistent predictor of body burden of lead, although the higher the blood lead level, the greater the amount of excretable (mobilizable) lead. It is recommended that an appropriate ratio of lead excreted in response to chelant Is equal to or greater than 0.5 based on this series of tests. A recommendation is also made to realign the Centers for Disease Control (Atlanta) guidelines for classification of risk. This realignment would coincide with a recommendation that mobilization tests be reserved for children whose blood lead levels ranged from 1.93 to 2.57 µmol/L (40 to 60 µg/dL). Those with higher levels would undergo chelation without prior mobilization studies.