Pulmonary agenesis, aplasia and hypoplasia are very rare major congenital anomalies. In the great majority of these conditions, diagnosis is usually made at or soon after birth. However, extremely rare asymptomatic cases may go unnoticed until adulthood. We present two asymptomatic patients with pulmonary agenesis in whom the diagnosis was delayed until their fourth and fifth decades, respectively. In both patients, ultimate diagnosis was coincidentally made based on abnormal appearance on chest X-rays obtained for other symptoms. Contrast-enhanced thorax CT and MRI angiography were found to be the most useful tools in their management.