Electronically controlled systems, originally developed for passenger cars, have been applied to trucks and buses since the early 1980's. With the increase of the objects for those applications their contents have become more and more sophisticated with rapid expansion and growth. This paper has summarized the results of observations on the background situations behind the applications of electronic control systems to trucks and buses in Japan. The status of the electronic applications, in particular to the powertrain, are explained and specific examples are provided. Future trends are also discussed.