A tissue processor for treating tissue samples comprises a process chamber (10) in which the tissue samples can be treated with at least one liquid. The process chamber (10) is formed as a vessel of a magnetic stirrer. In the process chamber, a stirring body (16) for stirring the liquid is arranged, wherein the stirring body (16) comprises at least one magnet (40a, 40b) with the aid of which the stirring body (16) can be set in rotation by a drive unit (20) of the magnetic stirrer, and at least one vane (28a to 28f) by which the liquid to be stirred is stirred when the stirring body (16) rotates. According to a first aspect of the invention, the stirring body (16) has at least three vanes (28a to 28f), according to a second aspect of the invention, the stirring body (16) has at least one further magnet (40b). The north pole (46) of the one magnet (40a) and the south pole (50) of the further magnet (40b) face the drive unit (20).