Objective:To evaluate from a hospital's perspective the costs and savings, over a 1-yr period, of implementing The Leapfrog Group's Intensive Care Unit Physician Staffing (IPS) standard compared with the existing standard of nonintensivist staffing in adult intensive care units. Design:Using published data, we developed a financial model of costs and savings for 6-, 12- and 18-bed intensive care units using conservative estimates for all variables. Sensitivity analyses, including a best-case and worst-case scenario, were performed to evaluate the impact of changing assumptions on the outcome of the model. Setting:Nonrural hospitals in the United States. Patients:All adult intensive care unit patients. Interventions:The IPS standard requires that intensive care units have a dedicated intensivist present during daytime hours. Outside of these hours, an intensivist must be immediately available by pager, and a physician or “physician extender” must be in the hospital and able to immediately reach intensive care unit patients. Measurements and Main Results:Cost savings ranged from $510,000 to $3.3 million for 6- to 18-bed intensive care units. The best-case scenario demonstrated savings of $4.2–13 million. Under the worst-case scenario, there was a net cost of $890,000 to $1.3 million. Conclusions:Financial modeling of implementation of the IPS standard using conservative assumptions demonstrated cost savings to hospitals. Only under worst-case scenario assumptions did intensivist staffing result in additional cost to hospitals. These economic findings must be interpreted in the context of significant reductions in patient morbidity and mortality rates also associated with intensivist staffing. Given the magnitude of its clinical and financial impact, hospital leaders should be asking “how to” rather than “whether to” implement The Leapfrog Group's ICU Physician Staffing standard.