The chemical composition of the volatile constituents from bracts and leaves of wild and hydroponically cultivated Origanum dictamnus were analysed by GC and GC-MS. Three different levels of nitrogen (100, 150, 200 mg/l), were used in the nutrient solution for the cultivation, using the Nutrient Film Technique (N.F.T). Carvacrol was the predominant compound in all cases. The essential oils were investigated for their antimicrobial activity against Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Escherichia coli, and Pseudomonas aeruginosa