Objective: The objective of this article is to offer current and evidence-based recommendations for the application of the most prominent tumor markers in various gastrointestinal cancers, especially Colorectal Carcinoma (CRC), pancreatic cancer and Hepatocellular Carcinoma (HCC). We focused on the most used tumor markers being used for diagnostic and therapeutic purposes for intestinal malignomas being Carcino Embryonic Antigen (CEA), Carbohydrate Antigen 19-9 (CA 19-9) and Alpha-FetoProtein (AFP) . We will describe their constraints and explain the usage in clinical practice and their significance in primary diagnosis, therapy monitoring and the early detection of recurrences, to enhance the quality of multidisciplinary care of cancer patients. Conclusion: Tumor markers have a clear role in clinical practice. In situations where imaging results are inconclusive, tumor markers offer additional confirmation of recurrence and prove valuable in postoperative surveillance and assessing the response to various therapeutic modalties. Due to their limited positive predictive value, specificity and sensitivity, they are not suitable for screening purposes. Knowledge of this markers is crucial to enhance the multidisciplinary care and treatment coordination for cancer patients. Therefore they should be included into future guidelines, surveillance-algorythms and staging-programmes for certain tumor-stages.