A rotary tiller, also known as a rototiller, rotavator, rotary hoe, power tiller, or rotary plough (in US: plow), is a motorised cultivator that works the soil by means of rotating tines or blades. Rotary tillers are either self-propelled or drawn as an attachment behind either a two-wheel tractor or four-wheel tractor. For two-wheel tractors they are rigidly fixed and powered via couplings to the tractors' transmission. For four-wheel tractors they are attached by means of a three-point hitch and driven by a power take-off (PTO).

In some parts of the world, the term "power tiller" can encompass the larger and similar appearing two-wheeled tractor, a machine which does, however, operate different attachments; in most English-speaking regions this difference is considered more rigid, as the term power tiller (and this article) refers solely to devices with soil cultivation as their primary and often only function.

agricultural Rototiller