Pulmonary hypertension (PH) is the condition of elevated pressures in the pulmonary circulation. PH can develop acutely in patients with critical illness such as acute respiratory distress syndrome, sepsis, massive pulmonary embolism, acute heart failure exacerbation, or after surgery. In a patient with cancer, unique etiologies such as myeloproliferative neoplasms, cancer-targeted therapies (tyrosine kinase inhibitors, proteosome inhibitors), or tumor emboli may result in PH. In cases of drug-induced PH, early recognition and withdrawal of offending agents may lead to improvement or resolution of PH. Progression of PH severity or acute right ventricular (RV) failure due to infection, thromboembolism, or hypoxemia may require an admission to an intensive care unit. Regardless of etiology, the development or worsening of PH may precipitate hypoxemia, hemodynamic instability, and/or right ventricular failure, which are challenging to manage and can be fatal. In select cases, rapid institution of advanced treatment modalities, such as intravenous or inhaled pulmonary vasodilators, inotropic support, or complete circulatory support, may be warranted. This chapter reviews the etiology, epidemiology, pathophysiology, clinical features, diagnosis, and prognosis of PH and presents a comprehensive analysis of PH and right heart failure management strategies in the critical care setting. We specifically focus on unique considerations in diagnosis and management of PH in patients with cancer.