AIM: To assess expression of matrix metalloproteinases 2 (MMP2) and MMP9 in gastric cancer, superficial gastritis and normal mucosa, and to measure metalloproteinase activity. METHODS: MMP2 and MMP9 mRNA expression was determined by quantitative real-time polymerase chain reaction. Normalization was carried out using three different factors. Proteins were analyzed by quantitative gelatin zymography (qGZ). RESULTS: 18S ribosomal RNA ( 18SRNA) was very highly expressed, while hypoxanthine ribosyltransferase- 1 ( HPRT-1) was moderately expressed. MMP2 was highly expressed, while MMP9 was not detected or lowly expressed in normal tissues, moderately or highly expressed in gastritis and highly expressed in cancer. Relative expression of 18SRNA and HPRT-1 showed no significant differences. Significant differences in MMP2 and MMP9 were found between cancer and normal tissue, but not between gastritis and normal tissue. Absolute quantification of MMP9 echoed this pattern, but differential expression of MMP2 proved conflictive. Analysis by qGZ indicated significant differences between cancer and normal tissue in MMP-2, total MMP-9, 250 and 110 kDa bands. CONCLUSION: MMP9 expression is enhanced in gastric cancer compared to normal mucosa; interpretation of differential expression of MMP2 is difficult to establish.