The nation's health-care system has strained to keep up with the COVID-19 crisis. This pressure is occurring alongside mismatches in the supply and demand for health-care professionals that predate the pandemic, shaped by the aging of the U.S. population, declining birth rates, and other trends. Immigrant professionals have long played a vital role at all levels of the U.S. health-care workforce, but not all of those with in-demand expertise have been able to put their skills to work. Large numbers of immigrants with health and medical college degrees are underemployed or out of work, with many facing challenges having their foreign-earned academic and professional credentials recognized. This issue brief explores the extent and nature of this skill underutilization, or "brain waste," among highly skilled immigrant health-care professionals in Illinois, a state with the sixth largest immigrant population in the country and one that boasts a long history of innovative immigrant integration efforts. The brief also examines key demographic, linguistic, and employment characteristics of the estimated 12,000 under- and unemployed immigrants with health or medical degrees in the state, and highlights opportunities to more fully leverage their skills. [This document was funded by the Walder Foundation.]