Oral examination alone cannot usually discriminate between benign, premalignant, and malignant lesions, resulting in delayed patient referral and a poor prognosis. Thus, any non-invasive technique that identifies oral premalignant and malignant lesions in a very sensitive and specific manner will surely assist doctors in the early detection and treatment of these illnesses. This study aimed to evaluate the effectiveness of acetic acid mouthwash and diffused light illumination (Microlux/DL(TM)) for visualizing oral mucosal lesions and identifying malignant or potentially malignant lesions.