Seseli gummiferam Pall. ex Sm. subsp. corymbosum (Boiss. & Heldr.) P.H. Davis (Syn: S. corymbosum Boiss. & Heldr.) (Umbelliferae) collected in southern Anatolia was investigated for the presence of coumarins. A new angular-type pyranocoumarin, corymbocoumarin (1), along with 5 known coumarins (2-6) were isolated from the aerial parts of this plant. Corymbocoumarin (1) was established to be (-)-(3'S,4'S)-3'-acetoxy-4'-isovaleryloxy-3',4'-dihydroseselin (1) and coumarins 2-6 were identified its (-)-(3'S,4'S)-3'-acetoxy-4'-angeloyloxy-3',4'-dihydroseselin (2), (+)-(3'S,4'S)-3'-hydroxy-4'-angeloyloxy-3',4'-dihydroseselin (d-laserpitin) (3), (-)-(3'S,4'S)-3'-angeloyloxy-4'-hydroxy-3',4'-dihydroseselin (4), 3'-acetoxy-4'-isobutyloxy-3',4'-dihydroseselin (5) and osthole (6), respectively, by spectroscopic methods. The structural elucidation and absolute configurations were determined by chemical correlations with known compounds.