Coroner and medical examiner systems in the United States conduct death investigations for most deaths that are sudden and unexplained, or which involve external causes such as injury and poisoning. They play a very important role in the criminal justice, public health, public safety, and medical communities, and they also contribute a substantial portion of autopsy-based mortality data to the state and federal mortality statistics systems. Death investigations often involve complex medical issues and necessarily require the involvement of appropriately trained physicians. Over the years, there has been a trend to replace the elected lay coroner systems with systems run by appointed, physician medical examiners. Presently, about 31% of counties in the United States are served by a medical examiners at the county, district, or state level. Between 1960 and 1989, there was considerable conversion to medical examiner systems, but this trend slowed in the 1990s. Since 2000, only 6 counties in the United States have converted to a medical examiner system, no states have converted since 1996, and 1 county has reverted to a sheriff-coroner system. Possible reasons for this decline are discussed, including legislative, political, geographical, financial, population-based, and physician manpower distribution factors. It is important to ensure that all death investigation systems have appropriate access to medically educated and trained physicians such as forensic pathologists.