OBJECTIVE: The incidence of ABPA was quite different according to the countries and the prevalence of ABPA has not been reported in Korea. In this study, we evaluated the prevalence of ABPA. In asthmatics with positive skin reactivity to Aspergillus fumigatus(Af). METHODS: Ninety asthmatics with positive skin reactivity to Af were enrolled. The ABPA were diagnosed by the Greenburg and Petterson's criteria or by the pathologic features of lung. RESULTS: Six cases out of 90 asthmatics (6.7%) were diagnosed as ABPA (ABPA group). Total IgE level were not significantly different between ABPA group and asthmatics with Af skin reactivity (BA group n=84). Five out of 6 ABPA had higher than 1000 ng/ml of total IgE and all six cases had more than 600/microliter of peripheral blood eosinophil counts. Only two cases had the positive immunoprecipitin band to Af antigen. Antibody index of Af specific IgE and IgG in ABPA group were 5.58+/-3.35, 2.75+/-1.29, respectively and coutruls were. Three cases of ABPA had central bronchiectasis, two case has only infiltrative lung lesions, one case with destructive lung lesions and another one cases have no pulmonary pathologic lesion at chest radiology but with the serologic evidence of ABPA. Although we could not find statistical significance, the FEV1(70.1+/-270% vs 87.8+/-23.2%) and PEFR (71.8+/-30.6% vs 95.0+/-26.5%) of ABPA group were lower than those of BA group. CONCLUSION: These results suggest that ABPA is not uncommon in Af sensitized asthmatics in Korea. We thought that initial examination of allergic skin test including Aspergillus should be emphasized for screening the ABPA in Korean asthmatics.