Lightweight, aircooled engines of 10 hp or less manufactured in Europe and Japan are surveyed. An attempt is made to isolate general trends. Newer engines and their main features are described. Both gasoline and diesel engines (rated at 300 rpm or above) are included in the survey. It is found that there are no startling novelties with the exception of theSachs-Wankelengine which, however, is not yet in production, but there are a number of interesting solutions to conventional problems.