A male farmer, 20 years old, from the countryside of the State of Piauí, developed acute respiratory infection. Despite adequate antimicrobial therapy, there was worsening respiratory manifestations demanding mechanical ventilation. Radiographs showed diffuse pulmonary infiltrates. PaO2/FiO2 was 58. Direct microscopy and culture from tracheal aspirates disclosed Coccidioides immitis. Autochthonous cases of coccidioidomycosis have only recently been described in Brazil, most of them from the State of Piauí. C. immitis has been isolated from humans, dogs and armadillos (Dasypus novemcinctus), and also from soil samples of armadillo's burrows. Therapeutic failure to antimicrobials and patient's origin from recognized endemic areas should alert for the possibility of acute pulmonary coccidioidomycosis.