Abstract The essential oils obtained by micro-distillation from aerial parts of Calamintha sylvatica Bromf. subsp. sylvatica (A) and and Calamintha sylvatica Bromf. subsp. ascendens (Jordan) P.W. Ball (B) were analyzed by GC and GC/MS. Cis-piperitone oxide (45.7%), terpinen-4-ol (8.6%), piperitenone oxide (5.5%) and trans-piperitone oxide (5.2%) were detected as main constituents in sample A; cis-piperitone oxide (21.8%), limonene (15.7%), piperitenone oxide (10.5%) and caryophyllene oxide (4.0 %) were found as main constituents in sample B.