Hyperthermia from exertion and environmental conditions during agricultural work manifests itself by various symptoms and may lead to death. From 1992 through 2006, 68 workers employed in crop production and related services died from heat-related illness. The crop worker fatality rate averaged 4 heat-related deaths per one million workers per year-20 times higher than the 0.2 rate for US civilian workers overall. Many of the agricultural workers who died were foreign-born. Foreign-born workers tend to have limited English language skills and often are not acclimatized to exertion in hot weather when beginning seasonal jobs. Increased recognition of heat hazards to agricultural workers, in particular, has stimulated concern among employers, workers, and public policy makers. California and Washington have led the nation in adopting workplace safety standards designed to prevent heat-related illnesses. These state regulations include new specific requirements for employer provision of drinking water, shade for rest or other sufficient means to recover from heat, worker and supervisor training, and written heat safety plans. Agricultural employers face practical challenges in fulfilling the purpose and complying with these standards. By their very nature the standards impose generic requirements in a broad range of circumstances and may not be equally protective in all agricultural work settings. It is vital that employers and supervisors have a thorough knowledge of heat illness prevention to devise and implement safety measures that suit local conditions. Ongoing risk-based assessment of current heat conditions by employers is important to this safety effort. Workers need training to avoid heat illness and recognize the symptoms in themselves and coworkers. Innovative management practices are joining time-honored approaches to controlling heat stress and strain. Research targeted to answer questions about heat accumulation and dissipation during agricultural work and audience-sensitive education to promote understanding of basic physiology and recognition of hyperthermia symptoms can aid in heat illness prevention. This review was prepared for the Agricultural Safety and Health Council of America/ National Institute for Occupational Safety and Health conference, "Be Safe, Be Profitable: Protecting Workers in Agriculture," Dallas/Fort Worth, Texas, January 27-28, 2010.