With the question in mind is superior vena caval obstruction a medical emergency, we reviewed 107 cases of superior vena caval obstruction in adult patients. We sought details of the time duration between the onset of symptoms and the treatment, and examined the complication and survival of patients with this disorder. Fifteen percent of the cases developed from benign causes. In 41 percent there was a previously recognized disease as the etiology. Benign disorders required longer to make the diagnosis. No serious complication resulted from the superior vena caval obstruction itself nor investigative procedures leading to the diagnosis despite, in some cases, a prolonged period between the onset of symptoms and the initiation of therapy. Prognosis and response to treatment were dependent on the underlying cause of the superior vena caval obstruction. Although several cases of tracheal obstruction were included in this series, we did not address the question of whether tracheal obstruction is or is not a medical emergency. No support was found for the notion that superior vena caval obstruction in itself represents a radiotherapeutic emergency.