The invention relates to a transparent/translucent liquid antimicrobial mouthwash composition that is substantially free of low molecular weight alcohol. It is a problem to include antimicrobial actives of natural origin (essential oils) which are generally substantially water insoluble materials in an aqueous composition that is transparent or translucent. One way of including such oils in water while ensuring transparency is to formulate them in a microemulsion composition. However microemulsion compositions generally require high amounts of surfactants and solvents especially low molecular weight alcohol. It is thus a challenge to formulate a mouthwash composition that is on the one hand effective in killing microbes while on the other hand has a transparent/translucent appearance while being substantially free of low molecular weight alcohol. The present inventors have solved this problem and have come up with a microemulsion mouthwash composition which meets all of the above objectives while being especially effective in killing S. mutans, a bacteria responsible for diseases in oral cavity.