Constituents of the volatile oil of Origanum vulgare ssp. viride growing wild in Kodjour (N. Iran) were studied using TLC, GC, GC/MS, and 1H-NMR methods. The oil was composed of monoterpenes and sesquiterpenes. The main components of the monoterpene fraction were linalyl acetate, sabinene, gamma-terpinene, trans-ocimene, and cis-ocimene. Low percentages of the phenolic monoterpenoids (thymol and carvacrol) were detected in the oil. The percentage of the identified sesquiterpenoid components was relatively high (44%). The main components of this fraction were beta-caryophyllene, caryophyllene oxide, germacrene D, and gamma-elemene.