Abstract: A container package for simultaneously staining a plurality of specimens arranged on the respective faces of a plurality of microscope slides comprises a slide holder for vertically supporting the slides at their upper ends in closely-spaced parallel relation and a generally rectangular body member having a generally rectangular upwardly-opening cavity for receiving the downwardly extending portions of the slides. The cavity has a height less than the length of the slides and the walls of the cavity conform closely to the perimeters of the slides. Guide walls are arranged in the corners of the cavity for maintaining a spaced relationship between the opposed end faces of the inserted slides and the cavity walls. A quantity of staining liquid partially fills the cavity, the depth of the liquid prior to insertion of the slides in the cavity being less than the distance between the specimens and the inserted ends of the respective slides.