The role of neutrophils migrated in the sputum and bronchoalveolar lavage fluid of intractable asthmatics is not difficult to understand. The production of leukotrienes (LTs) and superoxide stimulated by the calcium ionophores (CaI) from neutrophil-rich fraction of 29 intractable, 70 non-intractable asthmatics and 18 healthy subjects was examined by high performance liquid chromatography and a cytochrome C reduction method. Significantly larger amounts of LTC(4) and LTB(4) were produced by CaI in the neutrophil-rich fraction from asthematics, than in that from the healthy subjects (p<0.01). Moreover, a significantly larger amounts of LTC(4) was producted in the fraction obtained from the intractable asthmatics than in that from the non-intractable asthmatics (p<0.05). However, there was no significant difference in LTB(4) production between the two groups of asthmatics. The production of superoxide by concanavalin A was significantly increased in the neutrophil-rich fraction from prednisolone-within-10mg-dependent asthmatics than in those from prednisolone-over-10mg-dependent patients (p<0.01). There were correlations between the LTC(4) and LTB(4) production, and also between LTB(4) and superoxide production. LTs and superoxide released from inflammatory cells, especially neutrophils, may play an important role in the pathgenesis of intractable asthma.