Rapeseed, aka rape, oilseed rape, rapa, rapaseed and (in the case of one particular group of cultivars) canola, is a bright yellow flowering member of the family Brassicaceae (mustard or cabbage family).

The seeds of the rapeseed provides a quantity of oil ranging from 40 to 53% of dry matter, depending on the cultivar, and on the region, year and soil in which it is grown. Processing of rapeseed for oil production provides rapeseed animal meal as a by-product. The by-product is a high-protein animal feed, competitive with soya.The feed is mostly employed for cattle feeding, but also for pigs and chickens (though less valuable for these). The meal has a very low content of the glucosinolates responsible for metabolism disruption in cattle and pigs.

The rapeseed oil is used as a fuel for heating, light and recently as a fuel for automobiles with a diesel engine. In Germany more than 12.000 trucks and tractors are using pure chemically unmodified rapeseed oil as an alternative to the more expensive (bio)diesel. The diesel engines of these vehicles are specially adapted to this standardized DIN 51605 type of fuel. This always involves heating up the rapeseed oil to about 65°C just before injection into the pistons. Heating up the oil lowers its viscosity, making it easier to atomize.

For unmodified diesel engines rapeseed has to be chemically changed into biodiesel. This involves the use of methanol to replace the glycerol in the oil molecule. The resulting biodiesel is more similar to diesel in terms of viscosity and carbon chain length. The use of standardized DIN 14214 biodiesel from rapeseed is widespread and accepted. Almost all the produced biodiesel ends up as a mandatory 5% blend in regular diesel.

Rapeseed oil is also widely used for lubricants and to prevent dust in bulk handling of, for example, grains.

Premium value has the rapeseed oil when used as a food ingredient. It is used in margarine and different kinds of edible oils. Rapeseed oil contains both omega-6 and omega-3 fatty acids in a favorable ratio of 2:1 and is third only to Flax and Camelina oil in omega-3 fatty acid content. Rapeseed oil's proponents claim that it is one of the most heart-healthy oils and it has been reported to reduce cholesterol levels, lower serum triglyceride levels, and to keep blood platelets from sticking together.

China is the biggest producer of rapeseed oil, followed by India and Canada.

The price for rapeseed oil is linked to the price of crude mineral oil. In 2008 the price of rapeseed oil dropped with almost 50% following the price of crude mineral oil. In the last 10 months the price of rapeseed oil is gradually increasing to 850 Euro per Tonne.