It has been reported that S-1 can exert antitumor effects on various human cancers including oral squamous cell carcinoma (OSCC). However, little is known about the detailed mechanisms of the antitumor activity of S-1. In the present study, we determined whether S-1 could suppress the angiogenesis and growth of human OSCC cells in vitro and in vivo. The S-1 component (5-FU plus CDHP) significantly suppressed the growth and migration of OSCC cells and BAEC, which inhibited tubule formation in HUVECs in vitro. Also, S-1 inhibited the nuclear factor-kappaB (NF-kappaB) activity in human OSCC cells in vitro. Moreover, S-1 inhibited the expression of survival signal, phosphorylated Akt (p-Akt), and of two major proangiogenic molecules, vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2), in cells implanted into the subcutaneous tissue of nude mice. The decreased expression of p-Akt, VEGF and FGF-2 correlated with decreased tumorigenicity and decreased vascularization of lesions in vivo. These findings suggest that S-1 can suppress the angiogenesis and growth of OSCC cells by inhibiting the expression of p-Akt, VEGF and FGF-2 involved in the blockade of Akt/NF-kappaB pathway.