Metal plating with chromium and nickel has secured an occupational relation with asthma for which an allergic basis has been postulated but not confirmed. A worker who developed de novo asthma after plating with nickel and chromium but not other metals was subjected to inhalational challenge and immunoserologic tests to evaluate this association. He developed acute asthma to chromium sulfate and a biphasic asthma-like response to nickel sulfate. Radioimmunoassays incorporating the challenge materials revealed specific IgE antibodies to the provocative agents but not to another metal, gold, which he could tolerate. The findings support the postulates that bronchial reactivity can be specifically induced by fumes of metallic salts, even in a previously nonallergic individual, and that an IgE type I immunopathogenic mechanism is involved.