Sow mortality rates in the U.S. breeding herds have been increasing in recent years. Based on reports in the scientific literature, sow mortality rates started increasing by the mid- to late 1990s. This reality continues to be documented through database evaluation and reports from herd managers and producers. These trends are a clear challenge to herd veterinarians and producers in the swine industry in the U.S. and many other countries around the world. Sow mortality challenges are complex issues with multiple risk factors. This review covers reported incidences of increasing sow mortality, as well as etiologies and risk factors associated with sow mortality occurring in the modern lean-type sow. Gastro-intestinal, heart and locomotive problems, cystitispyelonephritis (inflammation of the urinary bladder and kidney), reproductive failure, prolapses, and additional disorders are consistently reported as common etiologies for sow mortality. Information on related risk factors such as population, sow housing, reproductive stage, and health status lead efforts to define and resolve sow mortality. Increasing sow mortality could well be taken as an indictment of modern production systems, of the genetically improved sows, or the knowledge and actions of animal caretakers. Prompt resolution of sow mortality is of critical importance and is a public expectation with respect to the ethical treatment and care of production food animals.