Although the relationship between chronic bronchopathies and gastro-esophageal reflux is known, the existence and role of nocturnal broncho-aspiration is controversial. 32 patients with chronic bronchopathy and 13 controls without digestive or respiratory symptoms were studied. Nocturnal broncho-aspiration was diagnosed by the demonstration of vegetable fibers in the morning expectorate and by the presence of radioactive pulmonary foci 15 hours following an isotopic meal. Vegetable fibers were found with equal frequency in both groups. On the other hand, positive pulmonary scintigraphy, reflecting nocturnal broncho-aspiration, was observed in 24 of the 32 patients (75%) and only in 2 of the 13 controls (15%) (p less than 0.001). Thus, broncho-aspiration is a frequent occurrence in chronic bronchopathies.