A new subspecies Seseli gummiferum Pall. ex Sm. subsp. ilgazense A.Duran, Ö.Çetin & M.Öztürk, subsp. nov. (Apiaceae) is described from Kastamonu province, Turkey. It was collected from the open Pinus sylvestris L. and Abies nordmanniana (Steven) É.Spach. mixed forest in the northern Anatolian region. An endemic apparently confined to the Ilgaz Mountain National Park, the new taxon is closely related to Seseli gummiferum subsp. gummiferum. Diagnostic morphological characters for closely similar taxa are discussed, and a key to the subspecies of Seseli gummiferum is presented. ITS (Internal Transcribed Spacer) region of the nuclear ribozomal DNA of closely related Seseli L. taxa and Pimpinella is used to constract phylogenetic tree by using BioEdit and Seaview Programme.