A retroperitoneal bronchopulmonary foregut malformation in a 62-year-old man is reported. The lesion was composed of mature lung tissue with randomly distributed bronchial structures and ciliated epithelium-lined cysts, some of which were lined with gastric mucosa. The histological features of this lesion were of both pulmonary sequestration and a bronchogenic, or foregut, cyst, and thus were a unique example of bronchopulmonary foregut malformation with pulmonary differentiation. This case is important in understanding the pathogenesis of foregut anomalies (i.e. bronchopulmonary foregut malformations), which range from pulmonary sequestrations to bronchogenic cysts and foregut duplication cysts.