The oral cavity contains rich and diverse microflora, known as oral microflora. Oral microflora usually presents within the biofilms attached to the various soft and hard tissue surfaces of the oral cavity. Oral microflora is beneficial to us and plays an important role in the normal development of the physiology. It also contributes to host defense; however, it can also have severe adverse effects for overall health. The present article aims to review the information regarding oral microflora in health and diseases. Recent updates regarding the oral microflora contribution in several common oral and systemic diseases are also briefly discussed.