The present invention relates to the field of floor treatment machines for scrubbing, polishing, sanding or burnishing floors, and in particular machines in which one or more driven rotatable work heads (such as scrubbing brushes) are provided for agitating the floor surface. In one aspect there is provided a walk-behind floor treatment machine comprising: a base portion provided with and supported by at least one rotatable work head for treating the floor, a handle portion for steering or guiding the machine along a working direction of travel and adapted to be pivotable with respect to the base portion, drive means for rotating the work head with respect to the base portion, floor-engaging wheel means for supporting the handle portion, the wheel means having a substantially transverse axis of rotation so as to permit travel in the working direction, the wheel means being coupled to the base portion by a linkage which permits vertical travel of the base portion and associated work head or heads with respect to the wheel means, but which provides transverse constraint to limit or prevent yawing of the base portion with respect to the wheel means, wherein a lower region of the handle portion is pivotably connected to the wheel means via an articulated joint, the arrangement being such that the handle portion may be manipulated to act on the wheel means so as to yaw steer the wheel means about a yaw axis defined by the floor-engaging contact of the wheel means, the yawing of the wheel means causing the base portion to yaw in response to yaw steering. The wheel means may comprise a wheel, roller or ball, preferably a single wheel, roller or ball, disposed at a lower region of the handle portion. The wheel means preferably has a fixed transverse axis of rotation.