The commercial development of car seat heating began in Sweden some fifteen years ago. Acceptance and customer demand for such an option has spread throughout European markets, with seat heaters currently supplied as standard equipment or options on Saab, Volvo, Jaguar, BMW, Opel and Mercedes. In Sweden all passenger cars produced for sale in that country are required to have electrical seat heating systems as a standard feature.The design of-seat heating systems is more complex and sophisticated than might be imagined. Current state of the art seat heating systems are much more than simple heating elements like those found in home heating blankets and pads.A high degree of human engineering goes into the properly designed seat heating system to only supply the heat loss experienced by a person's body and only at the major contact points in seat cushion and back.Fabric and leather each require a different solution due to the difference in insulating properties of each. Actual seat design and construction also must be factored into the effective heating system for optimum results.The heating elements must pass the same demanding physical tests that are applied to the seats themselves.The system described uses a thermostat operating as a temperature sensor. A relay is driven by an electric control unit with desired temperatures of the heating element set by a dash mounted rheostat. It can also be applied as a fully automatic system to insure heating whenever the low temperature limit is reached.Currently more than 100 different configurations are available and are both designed and produced using computer aided systems.Both comfort and health can be positively influenced with the properly engineered seat heating system described in the paper.