Abstract The oils obtained by steam distillation of the leaves and flowers of Hippomarathrum microcarpum (M. B.) B. Fedsch. growing wild in Iran were investigated by a combination of GC and GC/MS. Thirty-one compounds in the leaf oil, and 28 compounds in the flower oil have been identified. The main constituents of the leaf oil were β-caryophyllene (26.4%), γ-muurolene (19.0%) and Iinalool (6.1%); the major components of the flower oil were β-caryophyllene (18.5%), γ-muurolene (19.2%), thymol (6.9%), camphene (6.4%) and Iinalool (5.9%).