A part of the search for active agents against Cancer and AIDS involves in vivo testing. The National Cancer Institute (NCI) maintains the Animal Production Program to supply the necessary laboratory animals needed for this in vivo testing. Much of the testing is performed in pathogen-free laboratory animals such as the ones produced by the Animal Production Program contract colonies. Thus, a health monitoring contract is used to determine the health status of the Animal Production Program rodent colonies. The determination of the health status of the NCI Animal Production Program contract rodent colonies is the primary objective of this effort. This effort is accomplished by utilizing tests for serologic, bacteriologic, parasitological, pathologic and molecular services.