The air dried part of Cyclottrichium niveum L plant was subjected to hydrodistillation for 4 h using a Clevenger type apparatus to give yellow oils in 0.8 %. The constituents of mountain mint essential oil was determined via gas chromatography-mass spectrometry (GC-MS). Thirty-one constituents were identified in the oil, representing 98.53% of the total oil. Pulegone (49.23%), isomenthone (15.52%), neo-iso-menthol (12.67%), menthone (3.32%), β-pinene (3.31%), cis-isopulegone (3.13%) and menthol (3.0%) were established as major constituents of mountain mint. According to these reports, isomenthone and pulegone are the main compounds of Cyclotrichium niveum essential oil.