Gold standard treatment of squamous cell carcinoma (SCC) of the oral tongue remains surgical resection of the primary tumour with negative margins. The primary goal is the complete excision of the tumour with no residual cancer cells left behind. A microscopically positive surgical margin is associated with a higher risk for local recurrence and a poor clinical outcome. Close margins or the appropriate margin clearance from tumour remains a controversial debate in the literature. The most widely accepted definition of adequate margin distance for SCC of oral tongue is 5.0mm, but the precise cutoff at which the risk for local recurrence with a close margin approximates that of a microscopically positive margin remains unclear. The objective of this retrospective study on 381 patients was to determine an optimal margin cut-off for local recurrence-free survival. Patients with a margin of 2.3 to 5.0mm had similar recurrence free survival as patients with a margin of greater than 5.0mm. It was significantly affected only with surgical margins of less than or equal to 2.2mm in patients with SCC of oral tongue. As distance between the edge of tumour and the closest resection margin is used as an important factor in deciding an adjuvant treatment of head and neck cancer, this work is very important. If this new cut-off is used it may avoid unnecessary adjuvant treatment in many patients reducing accompanying side-effects and cost.