Hypersensitivity pneumonitis or extrinsic allergic alveolitis may be defined as an immunological pulmonary disease caused by a variety of antigens reaching the lungs through inhaled organic and inorganic dusts derived from different sources, although they are usually occupational. Farmer's lung and pigeon breeder's lung are probably the most well-known types of hypersensitivity pneumonitis worldwide. Esparto grass (Stipa tenacissima), which is a grammineous plant which is commonly found in the Mediterranean countries, has a wide variety of uses. Esparto fiber is used for the manufacturing of ropes, hemp sandals, rush mats and parkets; for decorative stucco plates, used on walls and ceilings. Esparto supports a large industry in Spain. The first reports referring to esparto dust as a cause of respiratory disease did not appear until the 1960s, and it was first described as a byssinosis-like disorder. The first cases reported, in which immunologic and challenge tests were used to confirm this association, were described 14 years ago and referred as hypersensitivity pneumonitis nominated as stipatosis. Later, a large number of cases of esparto dust-induced hypersensitivity pneumonitis were reported by different authors, so that esparto may be nowadays considered as the main substance causing extrinsic allergic alveolitis in Spain. Afumigatus has been revealed to be the main inducing cause of stipatosis but probably is not the only one since other microorganisms could be implicated. On the other hand esparto fibers may also cause occupational asthma. In this article the prominent clinical findings of this disease as well as the results of serologic, bronchoalveolar lavage (BAL) and specific inhalation tests are shown. A complete historical review of esparto-induced allergic respiratory disease is also described.