The present study was designed to examine in vitro antimicrobial and antifungal activities of the essential oil of Cyclotrichium niveum. The major constituents of the essential oil were determined as pulegone (50.46%) and iso-menthone (34.53%). The antimicrobial activity of the oil was also tested against gram-positive and -negative bacteria and fungus using a disc-diffusion method and the minimal inhibitory concentration (MIC) values. The oil showed remarkable antibacterial activity against Klebsiella pneumoniae and Staphylococcus aureus. The essential oil exhibited also, strong antifungal activity against Candida albicans.