Congenital unilateral absence of a pulmonary artery is a rare anomaly most frequently accompanied by other cardiovascular anomalies. We report a 10-year-old girl presenting with fatigue and recurrent hemoptysis who was initially misdiagnosed with idiopathic pulmonary hemosiderosis. Her symptoms did not resolve despite treatment so she was referred to our center for further evaluation. We carried out an angiography which revealed the absence of the right pulmonary artery and multiple collaterals originating from the right subclavian and right internal mammary arteries supplying the right lung. During the follow-up the patient developed a severe episode of pulmonary infection and pulmonary hypertension which responded well to medical treatment. Physicians should be aware of the congenital absence of the right pulmonary artery especially in patients presenting with recurrent respiratory symptoms. Although this condition is generally considered to have a good prognosis, close observation is mandatory in order to prevent further complications and comorbidities.