The tongue is referred to as 'the mirror of systemic diseases' as often the earliest signs of these diseases can be seen on it. This is similar to the 'face' being known as 'the mirror of mind' as it reflects the expressions of the mind. More recently, tongue prints displaying patterns of lingual papillae are used in medico- legal purposes for personal identification.The purpose to do this review is to reveal the mysteries of tongue and hidden facts associated with it. And to have a sound knowledge of 'the diseases of tongue and their cure' which would further develop our subject.