Secretion of gelatinases A (MMP-2) and B (MMP-9) from 21 tumoral explants of squamous cell carcinoma (SCC) and five samples of normal mucosa of the oral cavity is demonstrated here. The explants were cultured into fetal bovine serum- and phenol red-deprived medium for 48 hours. The gelatinases secreted into the medium were revealed and quantified by zymography and densitometry, respectively. The results showed high medians of the 66 kDa forms of gelatinase A in tumoral explants, in comparison to normal explants: 31.0 vs 5.9 densitometric units (DU) (p <0.01). There was also a relatioship between clinical response to neo-adjuvant chemotherapy and low activity of 66 kDa form of gelatinase A, as well as 84 kDa and 92 kDa forms of gelatinase B. The median of gelatinolysis of the inactive form of gelatinase A (72 kDa form) was higher in those patients who exhibited a complete response to neo-adjuvant chemotherapy. We conclude that gelatinase A is a useful and objective tool to evaluate the response to chemotherapy and the aggressiveness of carcinomas of the oral cavity.