A 52-year-old woman was presented with 2-week history of increasing dyspnea and dry cough. The chest radiograph revealed bilateral reticular infiltrates. Radiographic infiltrates were rapidly progressed and symptoms from hypoxemia were aggravated. The patient was intubated and bronchoscopy with transbronchial lung biopsies was performed. Biopsies revealed lymphatic vessels plugged by nests of metastatic adenocarcinoma. She died 11 days after admission despite of intensive ventilatory support. We had difficulties in the diagnosis of lymphangitic lung carcinomatosis at initial presentation of her illness because the progression was unusually rapid. Lymphangitic lung carcinomatosis should be included in the differential diagnosis of patients showing rapidly progressive interstitial radiographic findings. Also, transbronchial lung biopsy may be a useful tool to confirm the diagnosis.