The purpose of this study is to evaluate the factor structure of the Emotional Distress Inventory (EDI), a brief 15-item self-report measure of emotional distress in a sample of 238 cancer patients. The conceptual framework that guided the development of the EDI, factor structure,internal consistency, and convergent validity are reported. Emotional distress items were developed and administered to cancer patients who initiated chemotherapy and/or radiation treatments at Morton Plant Hospital Cancer Center in Clearwater, Florida, USA. Item responses were examined by Factor Analyses of Principal Components with promax rotations, which yielded three factors. Strong alpha coefficients and correlations between the EDI, HADS and BSI offer impressive evidence of internal consistency and convergent validity. The EDI presents three subscales that assess Anxiety/Depression, Hopelessness, and Anger Expression as components of emotional distress. We also discuss the important implications of these subscales, particularly the inclusion of anger expression and hopelessness, in the assessment of emotional distress in cancer patients. © Copyright 2010: de los Editores de Ansiedad y Estrés.