Background: Recently, we were able to demonstrate that tumour M2 pyruvate kinase (tumour M2-PK) is detectable in the faeces of patients with gastrointestinal (GI) cancer. In this study, an enzyme linked immunosorbent assay (ELISA) based on a different combination of monoclonal antibodies was used to investigate faecal samples of GI cancer patients [Germany]. Patients and methods: The ELISA was based on one antibody specific for tumour M2-PK and a second antibody reacting with tumour M2-PK, M1-PK and the tetrameric M2-PK. Faecal samples from healthy controls (n=15) and patients with inflammatory bowel disease (IBD; n=3), colorectal cancer (n=15) and gastric cancer (n=9) were examined. Results: Compared to controls, samples from patients with gastric cancer showed significant difference (elevated faecal PK in 80%; P=0.005); however, samples from patients with IBD and colorectal cancer did not show significant differences. Conclusion: If the present results can be confirmed in larger patient samples, this new test might provide an excellent screening tool for gastric cancer.