Airway fungal infections are often associated in asthmatics with the exacerbation of asthma symptoms. However, the pathomechanism of this phenomenon has not been fully understood. The aim of our study was to assess whether antimycotic treatment can influence the capacity of bronchoalveolar (BAL) leukocytes to release proinflammatory cytokines, which could contribute to increase in asthma severity. Ten patients with bronchial asthma complicated by airway fungal infections (Candida albicans and/or Aspergillus fumigatus) were included in the study. Seven asthmatics were treated with systemic and inhaled corticosteroids, whereas the remaining three with inhaled ones only. All subjects underwent several courses of therapy with antibiotics due to respiratory infections. BAL leukocytes obtained from the patients were cultured in the absence or presence of lipopolysaccharide E.coli (LPS) or Newcastle disease virus (NDV). The BAL procedure and measurement of the levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (II-6), interferon-gamma (IFN-gamma), and interferon-alpha (IFN-alpha) by specific bioassays were performed twice: before antimycotic treatment and after 3 weeks of therapy with 8 mg of nebulized fluoconazole and 400 mg of oral ketoconazole per day. The elimination of fungi from respiratory tract resulted in an apparent clinical improvement. This coincided with diminished production of TNF-alpha in response to LPS and the production of IFN-alpha in response to NDV, which were initially high and subsided significantly after antimycotic therapy (p = 0.035, and 0.011, respectively). Such changes were not observed in the case of IFN-gamma and IL-6. This may suggest that TNF-alpha as well as IFN-alpha are secreted by fungi-prestimulated leukocytes from the lower respiratory tract and may be involved in the processes of exacerbation of asthma complicated by fungal infections. Further analyses of relationships between changes in cytokine levels and clinical parameters indicated that IFN-alpha seems to be of particular interest in fungal stimulation of asthma.