Patient 1 was a 71-year-old man who had been admitted to our hospital with high-grade fever. Chest computed tomographic (CT) images revealed clear peripheral and high-density central areas. Abnormal laboratory findings included elevated LDH and hypoxemia. Interstitial pneumonia was suspected, and transbronchial lung biopsy (TBLB) confirmed the diagnosis of intravascular lymphomatosis (IVL). The patient succumbed before completion of chemotherapy. Patient 2 was a 65-year-old man admitted with high-grade fever. Abnormal laboratory findings included pancytopenia, hypoxemia, and elevated levels of LDH and soluble interleukin-2 receptor. Chest CT images revealed diffuse, mildly dense areas in the upper fields of both lungs. TBLB specimens yielded a diagnosis of IVL. Complete clinical remission was obtained with CHOP multiagent chemotherapy. Although IVL is usually diagnosed at autopsy, in these 2 cases an antemortem diagnosis was made on the basis of TBLB findings. Also, multiagent chemotherapy achieved a complete clinical remission in Patient 2.