The World Health Organization has clearly identified prevention and early detection as major objectives in the control of the oral cancer burden worldwide. At the present time, screening of oral cancer and its pre-invasive intra-epithelial stages, as well as its early detection, is still largely based on visual examination of the mouth. There is strong available evidence to suggest that visual inspection of the oral mucosa is effective in reducing mortality from oral cancer in individuals exposed to risk factors. Simple visual examination, however, is well known to be limited by subjective interpretation and by the potential, albeit rare, occurrence of dysplasia and early OSCC within areas of normal-looking oral mucosa. As a consequence, adjunctive techniques have been suggested to increase our ability to differentiate between benign abnormalities and dysplastic/malignant changes as well as to identify areas of dysplasia/early OSCC that are not visible to naked eye. These include the use of toluidine blue, brush biopsy, chemiluminescence and tissue autofluorescence. The present paper reviews the evidence supporting the efficacy of the aforementioned techniques in improving the identification of dysplastic/malignant changes of the oral mucosa. We conclude that available studies have shown promising results, but strong evidence to support the use of oral cancer diagnostic aids is still lacking. Further research with clear objectives, well-defined population cohorts, and sound methodology is strongly required.