Pain and dyspnea are the most prevalent and distressing symptoms in patients with terminally ill cancer. Evidences have accumulated for the effects of morphine on dyspnea, whereas little is known about the effects of oxycodone on dyspnea. We investigated the effectiveness of oxycodone for dyspnea in patients with terminally ill cancer. The injectable form of compound oxycodone (iOC) containing hydrocotarnine was administered continuously via subcutaneous route. We administered iOC to 136 patients. The effect on dyspnea was less conspicuous than pain, yet iOC was effective for dyspnea with varying degrees. None of the adverse effects observed were serious. These results suggest that continuous subcutaneous administration of oxycodone could be one of the reasonable alternatives in the management of dyspnea in patients with terminally ill cancer.