To highlight the variation in imaging and clinical manifestations of four cases of isolated unilateral absence of pulmonary artery presented in varied ages. Four patients with unilateral pulmonary artery agenesis were referred to our institution They underwent a series of investigations, including chest radiography, computed tomography and magnetic resonance imaging. Two of the four patients had absence of the right main pulmonary artery, while the remaining two patients had absence of the left main pulmonary artery. All patients showed a restrictive defect on pulmonary function tests. Radiography, CT and MRI confirmed the anatomy and the presence of multiple collaterals. Isolated unilateral pulmonary artery agenesis has a non-specific presentation. Awareness of this condition can lead to earlier diagnosis, with cross-sectional imaging making an important contribution.