(+)-Suksdorfin, (-)-isosamidin, (-)-3'-angeloyl-cis-khellactone, and a new pyranocoumarin, (3'S)-3'-angeloyl-4'-oxo-khellactone, were isolated from the aerial parts of Arracacia nelsonii.Their structures were established by chemical and spectroscopic means. - Key Word Index: Arracacia nelsonii; Umbelliferae; angular pyranocoumarins; khellactone derivatives; 3'-angeloyl-4'-oxo-khellactone.