BACKGROUND: Asthma is a chronic inflammatory disease of the airways characterized by a marked infiltration of ecsinophils in the bronchial mucosa. Asthmatic bronchial muosa produces many factors described as king chernotaetic for inflammatory cells. IL-5, RANTES, and MCP-1 alpha are the chemotactic factors for eosinophils, but their roles are controversiaL Recently eotaxin that is a potent eosinophil chernoattracttnt cytokine was detected in a guinea-pig model of allergic airway inflammation, and human eotaxin was cloned. Eotaxin is a specific chemoattractant for eosinophils, but its role in asthma is not confirmed. We examined the in vivo expression of a,taxin in bronchi of asthmatic patients. METHODS: 11 asthmatics and 2 normal controls were enrolled. All subjects were underwent brcnchcscopy with bronchial biopsies in 2nd or 3rd carina. RNA extraction from biopsy samples was done by acid-guanidium method. Semi-quantitaive RT-PCR was done for evaluation of eotaxin mRNA expression. The extent of eosinophil infiltrartion was evaluated by counting the eosinophils in submucosa in HPF of microscope. RESULTS: Eotaxin mRNA expressed in symptomatic, uncontrolled asthma. Steroid inhibited expression of eotaxin mRNA in asthma. Expression of eotaxin mRNA correlated with eosinohil infiltration in bronchial tissues. CONCLUISON: Expression of eotaxin mRNA increases in uncontrolled asthma and eotaxin is involved in the recruitment of eosinophils.