A comparative study was carried out between cinnamon oil and clove oil on the oral micro-biota causing dental caries. Cinnamon oil was found to be more effective than clove oil exhibiting broad spectrum of antibacterial activity inhibiting all the ten test bacterial species involved in dental caries. Cinnamon oil produced maximum inhibition zone of diameter (IZD) of 24.0 mm against Streptococcus mutans (major causative bacteria of dental plaque) as compared to clove oil (IZD = 13.0mm). This is contrary to the popular belief that clove oil is effective in tooth decay and dental plaque. This study shows the potential of cinnamon oil over clove oil in the treatment of dental caries. (www.actabiomedica.it).