BACKGROUND: In view of the recent opioid crisis, ways to promote safe and effective opioid-related practices are needed. Faster intravenous (iv) opioid infusion rates can result in increased adverse effects and risk for nonmedical opioid use. Data on best practices regarding safe iv opioid administration for cancer pain are limited. This study examined iv opioid bolus infusion practices and perceptions about opioids in cancer pain among 4 groups of inpatient oncology nurses. METHODS: An anonymous cross-sectional survey was conducted among oncology nurses working in medical, surgical, intensive care unit (ICU), and emergency department (ED) settings. An iv opioid bolus infusion speed less than 120 seconds was considered too fast. RESULTS: The participant response rate was 59% (731 of 1234). Approximately 58%, 54%, and 58% of all nurses administered morphine, hydromorphone, and fentanyl, respectively, in less than 120 seconds. The median morphine infusion speeds were 55, 60, 60, and 85 seconds for ICU, surgical, ED, and medical unit nurses, respectively (P = .0002). The odds ratios for infusing too fast were 2.04 and 2.52 for ED (P = .039) and ICU nurses (P = .003), respectively, in comparison with medical unit nurses, and they were 0.27 and 0.18 with frequent (P = .003) and very frequent use of a timing device (P = .0001), respectively, in comparison with no use. CONCLUSIONS: More than half the nurses working in the inpatient setting reported administering iv opioids too fast. ICU nurses administered opioids the fastest. Nurses who frequently used a timing device were less likely to infuse too fast. Further research is needed to standardize and improve the safe intermittent administration of iv opioids to patients with cancer. Cancer 2019;125:3882-3889.