The present study was carried out to evaluate the essential oil content and chemical composition of marjoram (Majorana hortensis Mnch.) plants grown at seven locations in Egypt (Giza, Beni-Suef, Faiyum, Minia, Assiut, Sohag and east Elowainat). The plant samples were collected from such regions, their volatile oils were extracted and oil content (%) in air-dry herbage was calculated. The E.O. composition was determined by using GC-MS and the percentages of its main components from the studied regions were compared. Moreover, antioxidant potential of TPC and TFC in plant extracts were determined. Results showed that the E.O content and its percentages of volatile oil's major components were changed also TPC and TFC differed among the collected plant samples grown at the studied locations as a result of variations in the geographical regions, soil characteristics and climatic conditions. Thus, the essential oil percentage in such sites varied from 1.2 to 3.0 %. The main components of oil; 4-terpineol,γ-terpinene,α-thujene,(+)trans-4-thujanol,sabinene,α-terpinene,linalool,α-phellandrene,β-thujene,(-)-B-caryophyllene,β-pinene,α-pinene and carvacrol can be interpreted as a factor connected to oil composition which is characteristics for commercial marjoram. The difference variability between the maximum and minimum values of each constituent among the locations gave an account in descending order: 27.57,11.76,10.56,10.46,8.81,8.66,6.01,4.01,3.39,2.17,0.91,0.89 and 0.21%, respectively. However, TPC ranged from 128.43 to 140.7 mg PEs/g dwt., and TFC from 86.61 to 117.22 mg/RU g dwt. According to this investigation, it is recommended to study the environmental factors of the location where marjoram plants will be cultivated since marjoram is considered to be a promising essential oil crop.