The essential oils of Satureja parnassica subsp. parnassica (samples A and B), were analyzed by means of GC/MS. From the fifty-seven identified constituents representing 98.5 % and 99.35 % of the oils respectively, (E)-caryophyllene, carvacrol and caryophyllene oxide were the major components of sample A (flowering stage), whereas in sample B (vegetative stage) major components were spathulenol, p-cymene and linalool. The oils were tested against Helicobacter pylori (HP), as well as against six aerobically growing bacteria. Both samples showed a moderate activity against Gram-positive bacteria; sample A oil showed greater anti-HP activity than sample B.