Abstract: Four new compounds of polyenynic type were isolated from the ether extract of Bupleurum longiradiatum Turcz. (Umbellifarae) and were named bupleurotoxin, bupleuronol, acetyl-bupleurotoxin and bupleurynol. Bupleurotoxin and acetyl-bupleurotoxin are the toxic principles of Bupleurum longiradiatum Turcz. The LD₅₀ for bupleurotoxin in mice (i.p. injection) is 3.03 mg/kg and for acetylbupleurotoxin 3.13 mg/kg.Physical, chemical and spectroscopic evidence supports bupleurynol as heptadecatren-(2Z, 8E, 10E)-diyne-(4,6)-ol-1, bupleurotoxin as 14-hydroxyl-bupleurynol, acetyl-bupleurotoxin as 14-acetoxy-bupleurynol and bupleuronol as 14-carbonyl-bupleurynol.