Allergic bronchopulmonary aspergillosis is reported in 2 (1.5%) of 131 workers occupationally exposed to Aspergillus fumigatus at the U.D. [Upper Doob] Sugar Mills, Shamli [India]. Twelve of the workers revealed Type I (9.2%) and 3 (2.8%) Type III skin hypersensitivity against the fungus. Serum precipitins were demonstrated in 2 out of 44 workers and positive sputum cultures in 26 out of 58 workers. Constitutional predisposition of the host may be a more important factor than the extent of exposure to the fungus in the development of allergic bronchopulmonary aspergillosis.