The procedure for Organisation of European Cancer Institutes (OECI) accreditation identified the formation of MDTs for the diagnosis and scheduling of primary treatment with integration of supportive care as a key strength at Istituto Nazionale Tumori (INT). The opportunities for improvement highlighted by the OECI peer review inspired a study on the evaluation of psychological distress, with a view to integrating this evaluation into global patient management and to defining standardized criteria for the provision of psychological services. This article describes the OECI accreditation experience at INT and the study conducted between January and May 2015 on the evaluation of patients' distress levels during cancer treatment, defining a score-based cutoff point that triggers the intervention of a psychologist. The Distress Thermometer was used as a tool for evaluating psychological distress, performed by nurses on admitting the patient. A total of 261 questionnaires were completed by patients admitted to the medical oncology and hematology departments, with an average distress value of 4.1, and 60% of patients experiencing clinically detectable emotional distress. Emotion-related problems had a significant association with a greater level of distress, while there were few reports of relationship issues as a cause of distress. As a result of the improvement initiative supported by the psychological distress evaluation study, we validated the screening questionnaire to be included at the initial patient evaluation stage with a cutoff point triggering the intervention by a psychologist at a score of ≥7.