Background/Aim: Pituitary adenomas are brain tumors with invasive properties. Epithelial-mesenchymal-transition (EMT) is a cellular process linked to the transformation to an aggressive cancer phenotype. In the present study, we investigated the expression of a panel of EMT markers, namely E-cadherin, N-cadherin, SLUG, SNA1 and TWIST in a cohort of human pituitary adenomas. Materials and Methods: Fresh-frozen human pituitary tumors (n=95) were collected immediately after surgery for histology. Gene transcripts of the EMT markers were quantified using quantitative-polymerase chain reaction (PCR) analysis. Levels of expression were analyzed against clinical, pathological, invasion and endocrine functions. Results: Levels of E-cadherin and N-cadherin had a negative and positive correlation with the appearance of intratumoral cystic lesions of pituitary tumors. E-cadherin and TWIST were associated with tumor size and staging. There was a significant link between SLUG/TWIST and the destruction of the sella fosa bones (p<0.030). EMT markers also showed links with the endocrine functions of pituitary tumors. In pituitary tumors, SLUG and SNA1 had significant correlation with N-cadherin. Conclusion: EMT markers are significant indicators of the appearance of cystic lesions, tumor progression, bone destruction and endocrine functions. These markers are valuable biomarkers in assessing the clinical course of pituitary adenomas.