Anti-larval effects of essential oil and methanolic extract obtained from leaves, stems and inflorescences of Hymenocarter longiflorus against Echinococcus granulosus were investigated and characterized with toxicological methods. Gas chromatography and mass spectroscopy (GC-MS) analyses have revealed the presence of 87 components in the essential oil of H. longiflorus. The main chemical components are α-pinene (10.16 %), 1,8-cineole (1.53 %), linalool (2.98 %), p-menth-1-en-8-ol (9.82 %), β-bourbonene (2.72 %), trans-caryophyllene (2.29 %), germacrene D (1.8 %), δ-cadenene (3.02 %), β-cadenene (1.43 %), hedycaryol (6.42 %), spathulenol (4.14 %), caryophyllene oxide (2.81 %), epicedrol (1.49 %), cis-3-hexenyl phenyl acetate (1.84 %), cubenol (1.46 %), δ-cadinol (18.49 %), β-eudesmol (4.56 %), isobutyl phthalate (1.88 %) and 2-(5-acetyl-2-furyl)-1,4-naphthoquinone (1.82 %). The essential oil and the methanolic extract exhibited significant toxic activity against the larvae of E. granulosus with LC 50 values of 79.68 and 135.88 μm/ml, respectively. These results suggest that H. longiflorus is a potential source of anti-larval constituents against E. granulosus. Further studies should be carried out for larvicidal effects of this plant against other species.