CASE 1: A 57-year-old man experienced severe dyspnea 24 hours after inhalation of waterproofing spray. Computed tomography (CT) revealed diffuse ground glass opacities in bilateral lungs. Pulmonary function tests showed mixed ventilatory disturbance with a low expiratory flow rate near the end of forced expiration and a normal diffusing capacity with normal functional residual capasity. The pulmonary function disorder was quickly improved by steroid therapy. CASE 2: A 59-year-old man smoked after inhaling waterproofing spray and soon developed dyspnea. The findings of CT were similar to those of case 1. His pulmonary function test revealed restrictive ventilatory disturbance and normal pulmonary diffusing capacity with low functional residual capacity. These findings improved without steroid treatment. However, it took more time for the pulmonary function to recover. There was probably specific inflammation around bronchioles, and the inflammation might have spread to the alveolar region in such cases with severe pulmonary function disorder. Steroid treatment seems to be useful to improve both the pulmonary function disorder and the clinical feature due to inhalation of waterproofing spray.