OBJECTIVE: The aim of this study is to consolidate screening function of special health examination for occupational asthma by investigating the results of respiratory function test as for workers who have been exposed to agents that cause occupational asthma. METHODS: To find out cases of occupational asthma, we carried out non-specific bronchial hyperresponsiveness (NSBH) test, peak expiratory flow rate (PEFR) test in appointed order for asthma-suspected cases among 4,602 workers that had a spirometry as a special health examination from April 2009 to July 2011. And we also performed t-test, one-way ANOVA, and multiple regression analysis to compare and analyse the associations between forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) and duration of exposure, kinds of agents, and number of exposed agents that cause occupational asthma. RESULTS: The case of occupational asthma was not found among 4,602 workers. And the result of a multiple regression analysis showed that organic compounds were correlated with FEV1/FVC (P=0.021). However, duration of exposure and number of exposed agents that cause occupational asthma were not associated with FEV1/FVC. CONCLUSION: For strengthening screening function of special health examination for occupational asthma, we can consider simultaneous operation of NSBH and PEFR, extending the PEFR term from 2 weeks to 4 weeks, thorough history taking on asthma. And as organic compounds may have effect on bronchial obstruction, so we need to concentrate on organic compounds-exposed workers for early screening of occupational asthma.