Published studies show that there are three types of pain during hospitalization: acute or chronic pain that motivates the admission and continues during hospitalization, pain that appears during hospitalization but was not the cause of the admission or associated with health care, and,pain that appears during the hospitalization associated with health care. To complete the description of patients with pain during hospitalization it has been suggested the existence of a fourth group of patients presenting with chronic pain that does not motivate the admission but persists and does not interfere during hospitalization. In a study evaluating the Italian population shows that the prevalence of pain is modified by marital status and age, and the intensity of pain increases with time evolution of pain and days of hospital stay. Some studies, mainly in Europe, show that the use of analgesics is high but the adherence to guideline recommendations for treatment of pain is low, or that the presence of pain is not recorded in the medical chart compared to the indication of analgesic treatment.