Hypersensitivity pneumonitis (HP), also known as extrinsic allergic alveolitis, is caused by a variety of environmental agents and may present as occult respiratory illness. HP represents a potentially curable subgroup of interstitial lung disease. This study was designed to examine a group of patients with HP due to a unique mechanism of environmental exposure. Five patients with HP were retrospectively identified, from our hospital records, admitted during the period of March 2007 to February 2011 with history of exposure to dug wells. The mode of exposure was specified as multiple entries into a dug well for different reasons. Other modes of exposure were considered as criteria of exclusion. All of the five patients had subacute HP based on available clinical, radiographic, immunologic, and supportive evidence and exposure. There were additional allergic bronchopulmonary aspergillosis-like features in one patient who did not have antecedent asthma. The evaluation of patient records indicated a fungal etiology. The air and soil from selected wells were tested for fungal organisms. Both settings grew Aspergillus as the predominant species. This novel mechanism of HP is labeled "dug-well lung" because the disease was attributed to exposure to dug wells. Lung disease may result from exposure to a dug well. Farmers or mechanics, climbing down these damp wells for a multitude of reasons, are prone to develop HP. The public health care personnel and farming community should be made aware of this potential occupation-related health hazard.