A marking apparatus for marking histology embedding cassettes includes a marking device for marking plastic surfaces, a gripping means to grip and release a cassette, and a movement organ to rotate the gripping means with respect to a first rotation axis perpendicular to a second rotation axis. The first axis is arranged such that it is situated in an ideal plane that is parallel to and interposed between the ideal planes in which the perpendicular surfaces of a cassette, gripped by the gripping means, are located, so that, upon rotation with respect to the first axis the first and the second perpendicular surfaces can alternately be located in front of the marking device. The second axis being arranged with respect to the gripping means such that, upon rotation with respect to the second axis, the oblique surface of the cassette can be in front of the marking device.