Hyperpolarized gas magnetic resonance imaging (MRI) of the lung provides high temporal and spatial resolution images of the air spaces of the lung and can be used to elucidate both lung ventilation and morphology. Because no ionizing radiation is involved, hyperpolarized gas MRI is ideal for the evaluation of pediatric lung diseases. In the article, we describe briefly the basic principles of hyperpolarized gas MRI, review the literature of hyperpolarized gas MRI in two pediatric lung diseases (asthma and cystic fibrosis), and discuss possible future clinical applications of hyperpolarized gas imaging in pediatric lung disease.