A 42-year-old man was admitted to the hospital because of wheezing and dyspnea that began 20 minutes after accidental exposure to irritant gas containing chromate at a chrome pellet manufacturing plant. The patient had a positive skin reaction to chromite (Cr2O3). Reduction of FEV1.0 was observed 120 minutes after Cr2O3 inhalation challenge. By 150 minutes after Cr2O3 inhalation, FEV1.0 had decreased by 32%. Chest X-ray film revealed no abnormalities. Histological findings of the lung tissue obtained by open lung biopsy revealed bronchospasm and peri-bronchial inflammatory cell infiltration without bronchiolar obstruction, and thus bronchiolitis obliterans was ruled out. This patient fulfilled the criteria of reactive airway dysfunction syndrome (RADS) proposed by Brooks; onset of symptoms very soon after a single exposure to an irritant, persistence of asthmatic symptoms, obstructive pulmonary dysfunction, and the presence of airway hyperreactivity to methacholine. During the initial hospital stay, asthmatic symptoms were relieved by intensive anti-asthmatic treatment including oral and parenteral corticosteroids. However, the patient's asthmatic symptoms have lasted for eight years and necessitate the use of systemic steroids, and regular use of inhaled steroids and bronchodilators. We know of no previous reported case of RADS after chromate exposure.