The aim of this study is to investigate the expression of the chromosomal passenger protein Aurora B and its activated (phosphorylated) form in a large series of human oral squamous cell cancers (OSCC) and to evaluate its clinical and prognostic significance. Western blotting analysis revealed overexpression of both Aurora B and Thr-232 Phopsho-Aurora B in OSCC lines as compared to normal keratinocytes and bladder cancer cells. Furthermore, protein expression was analysed by immunohistochemistry in 101 OSCC of different site, stage and histological grade and in normal peritumoural areas. The intracellular localization of Aurora B in tumour cells was mainly nuclear, especially in proliferative areas, and significant overexpression was found in tumours in comparison to normal peritumoural areas (P=0.012). Staining results were correlated with clinicopathological parameters and long-term follow-up, and a significant association was found between protein expression and tumour stage (stage II, III and IV vs stage I, P=0.030) and size (<2cm vs >2cm, P=0.010). Cox regression analysis confirmed a poorer disease-free survival in cases with high expression of Aurora B protein. Kaplan-Meier curves showed shorter time to progression in patients with high levels of Aurora B expression (p<0.05). Moreover, the tumoral group with nuclear Aurora B immunolocalization had the worst prognosis (P=0.0364 in disease free survival). Our results suggest that assessing Aurora B expression might help in patients risk stratification and serve as a novel therapeutic target in advanced OSCCs.