Oral squamous cell carcinoma (SCC) is the 13th commonest cancer worldwide, and the most common cancer in the Asian subcontinent due to the widespread habit of tobacco and betel nut chewing. Despite many advances in diagnosis and treatment, the survival statistics have only marginally improved. However our understanding of the disease process and transformation from pre-cancerous lesions of the oral mucosa to an invasive SCC cancer and their progression has expanded exponentially.There are many conditions of the oral mucosa that can progress to an invasive malignancy.  A thorough understanding of these conditions is a prerequisite for all those involved in the management of the diseases of the oral mucosa and head and neck region.The recognition and timely treatment of potentially pre-malignant conditions of the oral cavity can minimize the change to an overt malignancy in many patients through patient education, appropriate treatment and surveillance.