Oral squamous cell carcinoma (OSCC) is the 8th most common cancer globally with an incidence rate of 18 per 100 000 per annum in Australia. 1,2 Surgery forms the primary treatment of OSCC. 3 Risk stratification in deciding on the need for adjuvant therapy after resection of the primary OSCC is based on the presence of adverse histologic features such as extracapsular spread (ECS), close/involved margins, lymphovascular involvement (LVI), perineural involvement (PNI) and lymph node metastases. [4][5][6] Perineural invasion is defined when at least one of the two histologic features is present. Either tumour cells need to be present in any of the three layers of the nerve sheath or they need to encircle at least 33% of the circumference of a nerve. 7 Although PNI is generally acknowledged to be a negative prognostic factor, there is conflicting evidence in the literature regarding its association with recurrence and overall survival. [8][9][10][11][12][13][14][15][16] In the study by Crachiolo et al, 10 PNI-positive OSCC tumours were associated with decreased disease-specific survival (DSS) but not associated with differences in local or regional control rates. Liao et al 12 found that presence of PNI was not associated with decreased local control or overall survival.Currently, PNI is reported as being either absent or present, without any general consensus on classifying the type and extent of PNI.Evidence in the literature suggests that histopathologic subcategories