Peucedanum guvenianum Yıldırım & H.Duman is described as a species new to science. It is endemic to the West Anatolia region of Turkey. It is known from a single locality in İzmir Province. P. guvenianum shows similarities to P. longifolium, P. ruthenicum, and P. vourinense. Diagnostic morphological characters are discussed and compared with those of closely related taxa. It is easily distinguished from related species especially by its stem 130-220 cm tall, distinctly striate, densely branched from below the middle to upper part; basal leaves 28-40 cm long and 20-70 cm wide; bracts linear-lanceolate and erect; petals emarginate at apex; mericarp 7.2-14 x 4.3-8 mm, oblong to oblong-orbicular, $\pm$ two times longer from pedicel.