Background: Dyspnea is a frequent and devastating symptom among advanced cancer patients for which improved and low-cost palliative techniques are needed.Methods: A one-group repeated measures research design investigated the efficacy of guided imagery (GI) with theta music (θM) on dyspnea in advanced cancer patients. The intervention consisted of four periods: (a) pretest; (b) intervention with peaceful non-θM; (c) intervention with 10 min of GI with θM (GI/θM), with the first and last 3 min being θM only (i.e., the middle 4 min was GI/θM); and (d) posttest. Dyspnea outcome was measured with the Modified Borg Scale (MBS) for self-reported evaluation of dyspneic symptoms. Physiological parameters measured were pulse oxygen saturation (SpO2), end-tidal CO2(EtCO2), heart rate (HR), and respiratory rate (RR). Posttest qualitative data were obtained via interview for subjective patient experience.Results: Participants included 53 patients, 33% with lung cancer. GI/θM produced a significant decrease in MBS scores; 90% of the subjects gave positive qualitative reviews of GI/θM. SpO2did not change significantly over time. GI/θM significantly increased EtCO2, decreased RR, and decreased HR.Discussion: This study demonstrates that GI/θM is a useful intervention for palliative care of patients with dyspnea. θM alone was demonstrated to be effective, while soothing non-θM was not effective. GI/θM was more effective than θM alone. GI/θM should be considered low-cost end-of-life palliative care for dyspnea.