Patients with pain are not a new phenomena. For centuries, the incidence of pain has been well-documented. Responsibility for pain management has not been a universal priority for health care providers; however, pain management must be considered an integral part of the nursing role. The health care system must facilitate the improved management of patient's pain. A better understanding of the factors that underpin the effective management of a patient's pain is necessary. In this article, the theoretical foundation and conceptual model used in the expansion of this knowledge is presented. Further, the physiologic and pharmacologic principles related to this patient care issue are discussed. Appropriate consideration of the nurse's significant part in the management of pain is emphasized.