Attachment part of an electric toothbrush comprising a tubular connecting piece adapted to be connected to a neck of a handpiece of the toothbrush by axial movement along the longitudinal axis of the connecting piece and the handpiece. A radially movable latching element of the attachment part is adapted to lock the attachment part relative to the handpiece. The coupling between the handpiece and the attachment part includes a latching element and a latching contour which are adapted to lockingly engage with each other by radial movement relative to each other so as to axially lock the attachment part to the handpiece. Thereby, the latching element is provided with a circumferentially sloped unlocking surface for transforming a rotational movement of the connecting piece about the longitudinal axis of the tubular connecting piece into a radial movement of the latching element.
