IntroductionIsolated right pulmonary artery agenesis in an adult patient is an extremely rare condition that requires a high level of suspicion to make the diagnosis.Case DescriptionA 32-year-old woman presented to the emergency room with a 4-month history of recurrent respiratory infections. Chest radiography and computerized tomography (CT) revealed alveolar opacities on the medium and inferior right lobes. Fibreoptic bronchoscopy with bronchial aspirate was negative on both cytological and microbiological analysis. Due to the persistent of the imaging findings after a full course of a wide-spectrum antibiotic, an angio-CT was performed, revealing a complete stop at the level of the right pulmonary artery. Angiography confirmed the diagnosis of right pulmonary artery agenesis.DiscussionCurrently, the patient has no exertional dyspnoea, screening for pulmonary hypertension has so far been negative and no further respiratory infections have occurred. It is important to call attention to a major congenital malformation that may remain asymptomatic until adulthood.LEARNING POINTSUnilateral pulmonary agenesis is a rare entity that can present in multiple forms.A high level of suspicion and a thorough investigation is required for the diagnosis, with angiography remaining important even though chest angio-CT findings can suggest the diagnosis.A major complication of this condition is pulmonary hypertension, which can appear early in infancy or with conditions that modify the pulmonary circulation such as pregnancy, although previous pregnancies did not trigger pulmonary hypertension in our patient.