Hypersensitivity pneumonitis (HP) is a complex syndrome resulting from repeated exposure to a variety of organic particles. HP may present as acute, subacute or chronic clinical forms but with frequent overlap of these forms. A complex mixture of high & low molecular weight proteins from avian serum, feces and feathers produce the “Bird fancier’s lung” (BFL), also called Pigeon-breeder’s lung. Pigeons, Parakeets, Budgerigars and other small cage birds are usually involved, but the disease may also occur in individuals using feather-down duvets and pillows and even by indirect contact with birds in consorts (eg.handling others’ clothing). Pigeon serum proteins, feathers and droppings specific IgG has sensitivity of 100% and specificity of 84.62% at cut off of 30 mg/L for Bird Fancier’s hypersensitivity pneumonitis.