Abstract: The disclosure relates to a method and an apparatus for composting waste. The waste is deposited in a compost layer of a height of up to 9 m and the base surface dimensions of at least 5 m.times.5 m, preferably at least 10 m.times.30 m. The waste is fed from the compost layer to a rapidly rotating cutting roller which comminutes the waste and, under intermixing and vortex motion, flings it through a conditioning compartment for degasification and aeration, whereafter the waste is discharged and deposited in a new compost layer. The apparatus according to the invention substantially comprises a chassis with a motor, wheels and steering, on which there are mounted a feeding assembly, two feeding screws, a cutting roller between the feeding screws, a conditioning compartment whose bottom preferably consists of a conveyor belt, as well as a discharge assembly which preferably consists of a conveyor belt which is pivotal laterally and vertically.