E1AF is a newly identified ets-oncogene family transcription factor. Previous reports have noted that E1AF can upregulate promoter activities of several matrix metalloproteinase (MMP) genes and showed that invasive potentials of oral squamous cell carcinoma-derived cell lines are correlated with expression of E1AF and MMPs. The invasive phenotype is restrained by transfection with an antisense E1AF expression vector. Thus, E1AF is thought to be highly correlated with malignant potentials of cancer cells. However, little is known about E1AF expression and cancer cell malignancies in in vivo tumours. In the present study, 27 oral squamous cell carcinoma (SCC) specimens were examined using RT-PCR, Southern blot hybridisation and in situ hybridisation (ISH) and compared to the clinicopathological parameters. Among the 27 patients, E1AF was detected in 15 cases. E1AF mRNA was detected in 13 of 17 invasive SCCs, whereas the majority of SCCs not expressing E1AF showed an expansive growth pattern. Increased prevalence of E1AF-positive oral SCC was observed in cases with nodal metastasis. These results indicate that E1AF may be involved in cancer cell malignancies through its ability to promote invasive potential.