Abstract: A processing apparatus for tissue specimens, e.g. for histological examination, comprises a vessel defining a vapor space above heating means and a receptacle for volatile processing liquid and, near the upper end of that space, means for condensing vapor in the upper part of the space and for returning condensate to the liquid receptacle. Specimens are processed by suspension in the vapor space. There may be two or more receptacles for different processing liquids and means for moving these receptacles selectively between an accommodation space in the vessel and an operative position. Means is provided for sealing the vessel and for varying the atmospheric pressure therein. The apparatus further contains a heated wax bath for wax impregnation of processed specimens.