A patient with severe asthma induced by the inhalation of plexiglas dusts is reported. Inhalation testing against various industrial products to which he was exposed at work, showed a specific and reproducible asthmatic reaction to plexiglas dusts. Complete pulmonary investigations after positive challenge excluded associated alveolitis and demonstrated an immediate and a late obstructive response. The patient was not atopic and his clinical history did not suggest occupational disease due to chronic exposure. Reduction of the plexiglas dust exposure resulted in progressive improvement.