We evaluated the effect of ultrasonically nebulized furosemide (20 mg) on dyspnea uncontrollable by standard therapy in patients with terminal cancer. Dyspnea was evaluated using the Cancer Dyspnea Scale (CDS) before and 60 min after inhalation. Changes in arterial blood gases, hemoglobin oxygen saturation (SpO2), heart rate (HR), and respiratory rate (RR) also were evaluated. In 12 of 15 patients (80%), total dyspnea scores by CDS improved significantly after inhalation of furosemide (P = 0.007), especially concerning a reduced sense of effort (P = 0.013) and reduced anxiety (P = 0.04). No significant changes were observed in the partial pressure of oxygen in arterial blood (PaO2), the partial pressure of carbon dioxide in arterial blood (PaCO2), SpO2, HR, or RR. Inhalation of nebulized furosemide appears to be effective against dyspnea in terminally ill cancer patients.