In an apparatus for microwave-assisted preparation of specimens with a microwave generator (1), a microwave chamber for receiving specimens (5) to be processed, and a container arrangement (11) for a number of containers (9) for liquids, the microwave chamber is realized as a waveguide (2) that includes a first opening (7a) for introduction of a specimen (5) and a second opening (8a), preferably arranged at the bottom, through which a liquid container (9) is reversibly introduced into the microwave chamber while the specimen (5) is held stationary, until the liquid container thus introduced into the microwave chamber, and the liquid contained therein, surround the specimen (5).