Abstract: The method of changing the cage, including a bottom (31), grill (32) and lid (38), of a laboratory animal, includes the steps of: (a) providing a first rack (20) holding at least one clean bottom, grill and lid; (b) removing a clean bottom, grill and lid from said first rack; (c) assembling a clean cage from such bottom, grill and lid; (d) transferring a laboratory animal from a dirty cage to such assembled clean cage; (e) disassembling the dirty cage into its bottom, grill and lid components; (f) providing a second rack (20) having space for holding the dirty cage bottom, grill and lid components; (g) placing said dirty grill and lid on the second rack; (h) washing the dirty grill and lid while mounted on said second rack; (i) removing soiled bedding from the dirty bottom; (j) washing the bottom; (k) placing cleaned bedding in the washed bottom; and (l) placing said washed bottom with cleaned bedding on said second rack; thereby to change the cage of said laboratory animal.