Five new acridone alkaloids, citracridone-I (1a), citracridone-II (1b), citpressine-I (2a), citpressine-II (2b), and prenylcitpressine (3) have been isolated from the root bark of Citrus depressa as well as a known acridone alkaloid. The important Chinese drug "Chen-pi" has been used for treating heartache, abdominal pain, diarrhea, tussis, vomiting, inappetence and as an expectorant. The peel of various large amount Citrus species have been used as the source of Chen-pi in Taiwan, and one of them has been identified with the peel of Citrus depressa Hayata naturally grown in Orchid Island. This time, we collected the root bark of this plant in Orchid Island and studied the constituents. This report describes the isolation and the structural elucidation of five new alkaloids named citracridone-I, -II, citpressine-I, -II, and prenylcitpressine.