Background: Unilateral lung agenesis is an uncommon congenital abnormality, with a lack of reported accurate incidence estimates. Prognosis is also uncertain, with older literature reporting poor outcomes., Methods: The North of England register of congenital anomalies (Northern Congenital Abnormality Survey) records cases of congenital anomalies to mothers' resident in the region. We used the register to identify all patients with congenital lung agenesis born between 2004 and 2013 to calculate an accurate incidence estimate and report clinical outcomes with contemporary management., Results: Four patients with congenital lung agenesis were born during the study period, giving an estimated incidence in the North of England of 1.22 per 100,000 live births (95% confidence interval, 0.33-3.11). Two patients had associated congenital heart disease requiring corrective surgery, and one had musculoskeletal anomalies. All four patients are alive and well without a regular oxygen requirement., Conclusion: Contrary to previous reports, the medium term outcomes in our patients have been good, even when lung agenesis is associated with other congenital anomalies. Long-term prognosis with modern management remains unknown, and the potential for the development of pulmonary hypertension remains a concern. Birth Defects Research 109:857-859, 2017. © 2017 Wiley Periodicals, Inc., (© 2017 Wiley Periodicals, Inc.)