The Alternaria alternata-induced asthma model in the rat is used to assess the in vivo efficacy of anti-asthma drugs. In man, exposure to the fungal spore Alternaria alternata is a risk factor for asthma and can exacerbate clinical symptoms. This animal model features many similarities to human allergic asthma, including the presence of eosinophilic lung inflammation and the release of inflammatory mediators and cytokines primarily associated with Th2-type inflammation. Total and differential cell counts of inflammatory cells in the lung are performed on the bronchoalveolar lavage (BAL) fluid at various time points to observe the time course of inflammation and evaluate the effects of compounds. Additional services that can be combined with this asthma model include assessment of inflammatory mediators and histopathological evaluation. The model is robust, reproducible and sensitive to steroids (both oral and inhaled).