To clarify biochemical characteristics of tumor growth and/or invasion, the energy status of oral squamous cell carcinomas was investigated by measuring adenine nucleotides and correlating with morphological features. For this purpose, tumors originating from human squamous cell carcinoma of the tongue that had been transplanted into nude mice, and surgically resected human oral squamous cell carcinomas were used as materials. Adenine nucleotides, ATP, ADP and AMP, were measured with HPLC, revealing differences in relative concentrations between active and inactive regions of tumor growth and/or invasion. Specifically, the relative concentration of ATP was found to be high in regions where tumor growth and/or invasion seemed most active. Energy charge ratio was also high in those regions. These results suggest that adenine nucleotide metabolism may play some role in growth and/or invasion of oral squamous cell carcinoma.