Pulmonary veno-occlusive disease (PVOD) is an extremely rare condition in oncology practice. Although PVOD is clinically similar to pulmonary arterial hypertension, the conditions differ in terms of pathophysiology, management, and prognosis. This report discusses the case of a 47-year-old woman who developed dyspnea and fatigue after high-dose cyclophosphamide chemotherapy and autologous hematopoietic stem cell transplantation for relapsed lymphoma. The patient exhibited tachycardia, tachypnea, and hypotension, but other findings in the physical examination were unremarkable. The imaging studies showed no evidence of pulmonary embolism, but multiple ground-glass opacities and bilateral pleural effusions were observed on chest high-resolution computed tomography scans. In the right heart catheterization study, the mean pulmonary artery pressure and pulmonary vascular resistance were 35 mm Hg and 5.93 Wood units, respectively, with a normal pulmonary capillary wedge pressure of 10 mm Hg. Pulmonary function tests revealed a remarkable reduction in the percentage predicted value of diffusing capacity of the lungs for carbon monoxide to 31%. Lymphoma progression, collagen diseases, infectious diseases such as human immunodeficiency virus or parasitic infections, portal hypertension, and congenital heart disease were carefully excluded as these are also capable of causing pulmonary arterial hypertension. Thereafter, we reached a final diagnosis of PVOD. The patient was treated with supplemental oxygen and a diuretic during 1 month of hospitalization, which relieved her right heart overload symptoms. Herein, we present the patient's clinical course and diagnostic workup because misdiagnosis or inappropriate treatment can lead to unfavorable outcomes in patients with PVOD.