The invention relates to a unit for the treatment of histological samples. The unit comprises a treatment chamber (1), a device (2) for supplying and removing treatment agents (3, 3', 3'') to and from the treatment chamber (1), and a control system (4) for the performance of the treatment. The aim of the invention is to develop the unit in such a way that the need to carry out different treatments is taken into account in an economical manner. Towards this end, at least one other treatment chamber (5) is provided, by means of which treatments can be carried out independently from the first treatment chamber (1), the device (2) and the control system (4) also co-operating with that other treatment chamber (5).