Pneumonia caused by Mycoplasma pneumoniae is usually a mild and self-limited infection. Chest films usually show patch consolidation or interstitial infiltration in the lung. We recently encountered a case of fulminant Mycoplasma pneumonia which showed rapidly progressing extensive bilateral airspace consolidation with pleural effusion. A previously healthy 19-year-old female college student was admitted to the hospital because of fever and dry cough. Chest X-ray showed large areas of airspace consolidation in both lung with pleural effusion and rapid progression of the lung lesion. The diagnosis of Mycoplasma pneumonia was made from the serologic test. Here we report a case of Mycoplasma pneumonia showing unusual manifestation.