Intrathoracic metastases occur in 30-40% of patients with malignant disease. In this group 6-8% have lymphangitis carcinomatosa. This review examines the pathogenesis, investigation and treatment of lymphangitis carcinomatosa. The 40-49 years age group is most commonly affected. In 46% of patients respiratory symptoms are the initial presentation of the underlying carcinoma. The most common underlying primary tumours are breast (33%), stomach (29%) and lung cancers (17%). Approximately 50% die within 3 months of their first respiratory symptoms but those with a prostatic primary carcinoma may have good remission with adjuvant hormonal therapy.