According to the data of the literature, the prevalence of pain in cancer patients at various stages of the disease and the settings of care range from 38 to 51%, with an increase of up to 74% in the advanced and terminal stages. Despite published World Health Organization (WHO) guidelines for pain management, 42 to 51% of cancer patients receive inadequate analgesia and 30% receive no analgesics at all. A 3-year Research Project "Towards a Pain-free Hospital", which began one year ago, is ongoing at the National Cancer Institute of Milan. The research is organized in three subsequent steps. In the 1st one, a series of patient- and staff-oriented evaluation tools are used to assess the level of appropriateness of pain communication, assessment, management and control of the in-patients. The 2nd step will implement a number of continuing educational interventions aimed at improving patient awareness and staff knowledge of the appropriate pain assessment and management in order to respond to the patient's pain problem. In the 3rd step, all the assessment tools used in step one will be applied again to establish the prevalence of pain, the causes and intensity and patient satisfaction with pain management and to evaluate the impact of the interventions performed during the 2nd step regarding the overall ability of our hospital to tackle pain emergency in the hospitalized cancer population. The results relative to the 1st step are herein reported, in particular as regards the study on prevalence, causes, severity of pain, the interference of pain with sleep, mood and concentration, the use of pain medications and the relief obtained, the structural validity and internal consistency of the assessment tool used. A total of 258 patients hospitalized for at least 24 h were interviewed by 9 physicians using a brief structured questionnaire prepared ad hoc: 51.5% of the patients presented pain during the previous 24 h caused by surgery (49.6%) or by the tumor mass itself (29.3%). Out of the 133 patients with pain, a high degree (much or very much) of pain at rest was present in 27.1% and pain on movement in 30.8%; 31.6% did not take any analgesic treatment, and 14.3% of the latter reported a high degree of pain at rest and 21.4% on movement. Pain interfered with sleep from much to very much in 28.8% and with irritability and nervousness in 15.9% of the patients. In the 91 patients taking analgesics, 57.2% reported a high degree of pain relief. A high degree of pain and interference, however, was associated with low relief levels. The assessment tool used was shown to have a good structural validity and internal consistency (Chrombach alpha index of interference scale = 0.73). Although the Milan Cancer Institute has the longest tradition in Italy of pain assessment by means of validated tools and pain management according to the WHO guidelines and educational efforts in this field, the results of the study clearly show that it is necessary to persevere with continuing educational and informative programs in order to reduce the frequency and severity of pain and thus improve the quality of life of in-patients.