The objective of this study is to retrospectively assess the clinical relevance, i.c. the event of a local recurrence, in patients surgically treated for tongue and floor of mouth squamous cell carcinoma when tumour cell are observed histopathologically at a distance of less than 0.5 cm. Furthermore, the pattern of invasion and the presence or absence of perineural spread were recorded. A total of 68 patients, surgically treated because of a tongue or floor of mouth squamous cell carcinoma, were examined. Patients in whom any degree of epithelial dysplasia was observed in the mucosal surgical margins had been excluded beforehand. Local recurrence occurred in 2 out of 30 patients with a free surgical margins >0.5 cm and in 3 out of 38 patients with a free surgical margin <0.5 cm, the difference being not statistically significant. Apparently, the presence of tumour cells within a distance of less than 0.5 cm, but not into the deep surgical margin, does not necessarily seem to require additional treatment. The pattern of invasion and the presence or absence of perineural spread were not significantly related with local recurrence either.