Proteomic analysis recently suggested aberrant psoriasin (S100A7) expression in oral squamous cell carcinoma (OSCC). In this study, OSCC specimens and matching normal oral tissues from 45 patients who had undergone ablative surgery were examined. Increased psoriasin expression at mRNA level was observed in OSCC samples by quantitative real-time RT-PCR (p=0.015). Immunofluorescence analysis with psoriasin antibody confirmed these observations. Moreover, significantly increased mRNA ratios between malignant and normal samples were correlated with early UICC stage (p=0.006), T1/T2 tumour classification (p=0.043), absence of cervical lymph node metastasis (p=0.027) and age under 65 (p=0.009). Additionally, well-differentiated tumour tissues demonstrated a significantly higher psoriasin expression than moderate and poor differentiated carcinomas (p=0.018). Based on this data, we conclude that psoriasin is a positive marker for oral cancerogenesis and early tumour progression.