Late presentation of congenital diaphragmatic hernia (CDH) is unusual, especially in patients with cystic fibrosis (CF). To our knowledge, cases of CDH in CF patients and the combined effects on lung function have not been previously described. Here we report two cases of late presenting CDH in CF patients and describe effects on lung function. Late presentation of CDH in CF patients can cause gastrointestinal or respiratory symptoms and requires a high index of suspicion as well as proper interpretation of imaging. In patients with CF and CDH, lung function abnormalities could include obstructive, restrictive defects, or combined defects.