bnormal connections between distal portions of the respiratory airways and other anatomic structures usually produce significant pulmonary compromise. These interconnections may have an acute onset and lead tO) catastrophic consequences. Subacute or chronic presentations may also occur and will be emphasized in this review. It is usually not possible to localize the precise anatomic location of such tracks. Therefore, the generic term, “bronchial fistula’ will be used even though the actual interconnection may be distal to true bronchi or may be unknown. Tracheal fistulas will be omitted from this discussion. The frequency of bronchial fistulas in most disease states is unknown but their occurrence is unusual. The poor prognosis uniformly associated with longstanding fistulas complicated by infection, however, mandates their inclusion in the differential diagnosis of a large number of patient presentations. The consequences of regional or systemic infection, hypoxemia, and progressive lung injury due to persistent contamination of the pulmonary parenchyma by foreign material may produce significant morbidity. For the purposes of this review, bronchial fistulas will be grouped as those joining the lung with abdominal organs, the pleural space, vascular structures including the heart, and the central nervous system.