Forty six patients clinically suspected to have aspergillus lung disease [bronchial asthma 17, allergic broncho-pulmonary aspergillosis (ABPA) 22, aspergilloma 7] were evaluated by Phadebas RAST, Phadezym RAST (ELISA) and avidin-biotin ELISA for determination of specific IgE. Smear, culture, skin test against aspergillin, precipitin test and Enzygnost (total IgE) confirmed the diagnosis in 7 patients of extrinsic asthma due to conidia of Aspergillus spp., 17 for ABPA and 7 for aspergilloma among the clinically suspected patients. Specific IgE against Aspergillus fumigatus antigen was detected in 100 per cent patients of extrinsic asthma and 64.7 per cent of ABPA patients. No specific IgE could be detected in patients with aspergilloma. In patients other than those with, aspergilloma the detection rate of specific IgE was 50.0 per cent by radio-allergosorbent test (RAST), 62.5 per cent by ELISA, 66.7 per cent by avidin-biotin ELISA. Thus ELISA or avidin-biotin ELISA could replace the radioimmunoassay procedure for detection of specific IgE.