Tongue is highly specialized muscular organ of oral cavity. It shows a wide degree of clinical changes in systemic and local disease and has been used as an indicator of health. Great interest was shown to the tongue as an aid to the diseases, especially of the digestive system and hence the tongue has termed as a “mirror of the stomachs conditions". The educated eye of the clinician may recognize subtle evidence of important systemic diseases or infections, the initial manifestations of cutaneous disorders are of significant local problems. The detection of these abnormalities can be achieved only by those who recognize normal oral structure and their anatomic variation. Timely recognition allows for the prompt institution of appropriate therapy for disorders, resulting in better prognosis. This book act as a guide and an important diagnostic aid for all oral practitioners, helping them to diagnose and treat the diseases of tongue effectively.