Penicillamine was administered, per os, in patients who had been working with lead for several years, showing signs and symptoms suggesting chronic lead intoxication, so as to evaluated the test of lead chelation. A positive response allowed further treatment. Daily elimination of urinary lead, delta-aminolevulinic acid and coproporphyrin were evaluated. Weekly assays of hematic lead, protoporphyrin IX and the activity of the enzyme delta-aminolevulinic acid dehydratase were performed. The result show penicillamine to be an alternative to ethylene diamine tetra acetic acid in the chelatable lead mobilization test and prove that it is an excellent alternative in the treatment of chronic lead intoxication.