The current trend of treating chronic nonmalignant pain with opioid therapy means that pain management nurses are increasingly involved in the care of patients who are prescribed and using potent opioid analgesics on a daily basis. Although demonstrated to be quite effective in certain patients, sanctioned access to these medications brings with it risks for abuse, addiction, and diversion. Urine toxicology analysis is a valuable, yet underutilized, tool to monitor patterns of medication use and potential use of illicit drugs to evaluate the effect of these on health outcomes. This review provides a guide for the use of urine toxicology in the nursing management of chronic pain patients on opioid therapy, detailing the information provided by urine toxicology analysis, the benefits and limitations of urine drug testing, principles of sample collection, and correct interpretation of findings. It is emphasized that the results of urine toxicology analysis should never be used in isolation to identify abuse, addiction, or diversion, and that patterns of medication and other drug use should always be evaluated with respect to evidence of improved functionality. Nurses involved in the care of patients with chronic pain are encouraged to consider urine toxicology analysis as an integral component in care plan for those on chronic opioid therapy, and to knowledgeably implement and interpret this powerful tool in the practice of pain care.