Abstract: An animal holder frame for use with mice, rats and other long-tailed animals used in laboratory experimentation includes a horizontally disposed supporting base section on which an animal may stand or crouch. At one side of the base is vertically disposed a rack member formed with aperture means of a size suitable for admitting an animal's tail, perineum and gluteal regions. Peg means horizontally disposed in the rack in a position immediately adjacent to the outer side of the aperture means provides holding means to which the tail of an animal may be taped or otherwise detachably secured.