Inhibins are dimeric glycoproteins, composed of an alpha-subunit (inhibin-alpha) and one of two possible beta-subunits (betaA or betaB), with substantial roles in human reproduction and in endocrine-responsive tumours. The aims of this study were to determine the distribution of inhibin-alpha, -betaA and -betaB subunits in malignant human endometrial tissue and the assessment of an association with specific clinicopathologic tumour features and clinical outcome. A series of 302 endometrial cancer tissue samples were immunohistochemically analysed with monoclonal antibodies against inhibin subunits. The inhibin-alpha subunit showed a significant association with histological grading, surgical staging, lymph node status and diabetes in patients with endometrial cancer. Interestingly, loss of inhibin-alpha expression resulted in a poorer survival of endometrial cancer patients. Additionally, survival analysis demonstrated that inhibin-alpha immunoreactivity was an independent prognostic factor for progression-free survival, cause-specific survival as well as for overall survival. In contrast, although inhibin-betaA- and -betaB subunits showed a significant association between endometrial histological subtypes and histological grading, both subunits were not found to be associated with survival in endometrial cancer patients. Therefore, inhibin-alpha immunostaining might be used as a simple and efficient marker to identify high-risk patients leading to the selection of patients for an aggressive adjuvant therapy.