BACKGROUND Incomplete surgical removal of cancer is believed to be the main cause of local recurrence and high mortality. This study assessed the use of optical technology (namely optical coherence tomography [OCT]) in examining oral squamous cell carcinoma (OSCC) resection margins to assess if this modality could guide the surgeon during surgical resections. MATERIALS AND METHODS Twenty-eight T1-T2 N0M0 oral squamous cell carcinoma patients participated in this study. Nineteen patients were males and nine were females. The majority of lesions were in the ventro-lateral tongue, floor of mouth, retromolar trigone and the buccal mucosa. Following tumour resection, the specimen resection margins were optically scanned in the immediate ex vivo phase. Two independent assessors commented on the four resection margins of each specimen. The findings were then compared to the corresponding gold standard histopathology. The average epithelial thickness for both tumor-free and tumor-involved margins was also calculated. RESULTS The pathology reports of the 112 margins revealed 90 tumor-free margins and 22 tumor-involved margins. Examining the data from both senior operating surgeons (assessors), the overall sensitivity and specificity was found to be 81.5% and 87%, respectively. Whilst the positive predictive value was 61.5% and the negative predictive value was 95%. OCT accuracy for the first assessor was 88% and for the second assessor 84%. The assessors' inter-observer agreement was "very good" for superior, inferior and medial margins; while agreement on the lateral surgical margin status was "good". Using OCT, the mean epithelial thickness at the tumor-free resection margins was 360 μm; while, it was 567 μm for the tumour-involved margins. CONCLUSION OCT is a valuable tool in the assessment of surgical margins. Tumour-involved margins can be identified by architectural changes and increase in epithelial layer thickness on the OCT image. Further studies are required to assess tumour margins in vivo.