A worker with occupational exposure to aluminum powder developed asthmatic symptoms three years and six months after starting work. Skin tests (prick and intradermal) to aluminum chloride (AlCl3) were negative. Inhalation challenge test with 10 mg of aluminum powder and 10 mg/ml of AlCl3 solution induced an early asthmatic response. Sodium cromoglycate pre-treatment reduced AlCl3-induced bronchoconstriction. Neutrophil chemotactic activity was markedly increased one and seven hours after the challenge procedure, which was lessened with sodium cromoglycate pre-treatment. Aluminum can induce occupational asthma in exposed worker, which may be mediated by a non-immunologic mechanism and the possible role of neutrophils was suggested.