The essential oil was obtained by hydro distillation from the herb of marjoram (Majorana hortensis Möench) cultivated in the north of Iran. The oil content was 1.8% w/w based on dry weight. The oil was analyzed by capillary GC and GC/MS. A total of 24 components were identified by GC-MS analyses, the main components representing 99.2% of the oil was identified as terpinene-4-ol constituted (21.3%), trans-sabinene hydrate (14.8%), cis-sabinene hydrate acetate (10.7%), γ-terpinene (10.7%), α-terpinene (7.3%), sabinene (5.7%), α-terpineol (4.7%), cis-sabinene hydrate (4.5%), limonene (3.0%) linalyl acetate (3.0%) and terpinolene (2.6%). The results show that an acceptable content and composition of the oil is possible if marjoram is cultivated in north of Iran.