Abstract An oil of Calamintha nepeta (L.) Savi ssp. nepeta var. subisodonda (Borb.) Hayek obtained by hydrodistillation was analyzed by GC and GC/MS. Eleven constituents were identified (96.5%). The main constituents in the oil were pulegone (75.5%), piperitenone oxide (6.0%), menthone (5.3%) and menthol (4.3%). The microbial activity of the oil was screened against Aspergillus niger, Escherichia coli, Staphylococcus aureus, Salmonella enteritidis, Bacillus subtilis and Pseudomonas aeruginosa. It was found that all mentioned microorganisms were sensitive to the oil.