This study is the first chemical investigation of Ferula mervynii M. Sağıroğlu & H. Duman, an endemic species to Eastern Anatolia. The isolations of nine compounds including six previously undescribed sesquiterpene esters, 8-trans-cinnamoyltovarol (1), 8-trans-cinnamoylantakyatriol (3), 6-acetyl-8-trans-cinnamoyl-3-epi-antakyatriol (5), 6-acetyl-8-trans-cinnamoylshiromodiol ( 6), 6-acetyl-8-trans-cinnamoylfermedurone ( 7), and 6-acetyl-8-transcinnamoyl-(1S),2-epoxyfermedurone (8), were described along with three known sesquiterpene esters, 6-acetyl-8-benzoyltovarol (2), 6-acetyl-8-trans-cinnamoylantakyatriol (4), and ferutinin (9). The structures of novel compounds were elucidated through extensive spectroscopic analyses and quantum chemistry calculations. The putative biosynthetic pathways for compounds 7 and 8 were discussed. The extracts and isolated compounds were tested for cytotoxic activity against the COLO 205, K-562, MCF-7 cancer cell lines, and Human Umbilical Vein Endothelial Cell (HUVEC) lines using MTT assay. Compound 4 showed the highest activity against the MCF-7 cell lines with an IC 50 value of 16.74 � 0.21 μM.