In this study, we investigated the activity of matrix metalloproteinase (MMP)-2 and -9 by gelatine zymography, immunostaining and in situ gelatine zymography in 30 oesophageal squamous-cell carcinomas. The gelatinolytic activity in situ was detected in all cases with different patterns of localisation. Significant gelatinolysis by stromal cells adjacent to tumour nests was found in 12 cases. Strong gelatinolytic activity appeared within the tumour nest itself in 13 cases. In the other 5 cases, both stromal cells and tumour cells showed the gelatinolytic activity. Gelatine zymography demonstrated a correlation between vascular invasion and activation of MMP-9. It also demonstrated a correlation between lymph node metastasis, lymphatic or vascular invasion and activation of MMP-2. These results suggest that MMPs play an important role in the invasion of oesophageal carcinoma.