The volatile constituents of Nepeta septemcrenata Ehrenb. herb growing in Egypt were prepared by hydrodistillation of the fresh herb and analysed by GC/MS. Sixteen major compounds (represent 94.96% of total) were detected and identified. They contain ten oxygenated compounds (70.67%) and six hydrocarbons (24.29%). The major oxygenated compounds were 1,2 benzene-dicarboxylic acid dibutyl ester (33.16%) and 4-methyl-2,6ditertbutyl phenol (23.30% w/w), while the major hydrocarbon is 4-nonyne C9H16, (9.00%). The volatile constituents had promising antimicrobial activities against some tested microorganisms.