Campanula leblebicii Yildirim (Campanulaceae) is described here as a new species. Diagnostic morphological characters, a full description, and detailed illustrations are given herein. C. leblebicii is restricted to the caldede Mountain in Kentalpapa district of Izmir Province in western Anatolia, Turkey. According to its morphological features, it belongs to Campanula L. subgenus Campanula section Rupestres (Boiss.) Charadze. It shows morphological and ecological similarities with C. mugeana Yildirim, belonging to C. section Quinqueloculares (Boiss.) Phitos., and to C. koyuncui Duman and C. teucrioides Boiss. belonging to C. section Rupestres. However, C. leblebicii is easily distinguished from these taxa, especially by its glabrous habit; stigma, 3-lobed, and capsule, openby 3 basal valves, shiny, and never concealingby enlarged appendages (from C. mugeana); smaller calyx appendages; capsule never hidden by enlarged calyx appendages, and habitat phyllite-schistose rocks (from C. koyuncui); entire leaves, calyx appendages minute, never enlarged after anthesis (from C. teucrioides).