There is documented evidence that infection in laboratory animals can often influence the outcome of experiments. All infections, apparent or inapparent, are likely to increase biological variability. As a research project concerning the diversity and distribution of parasites of rabbit and guinea pig in a conventional laboratory animal house, about 87 rabbits (from 700 ) and 105 guinea pigs (from 1500 ) were selected randomly from a Research, Production & Breeding of Laboratory Animals Department. Samples were collected between 19.02.2010 and 20.05.2011. The samples and animals were examined by dissection and flotation methods. In this study only one species of nematodes (Passalorus ambiguus: 6.9%); one species of protozoa (Eimeria spp.: 21.8%) in rabbits and one species of nematodes (Paraspidodera Uncinata: 24.7%); one species of protozoa (Balantidium coli: 11.4%) in guinea pigs were identified. However, there was not any cestodes or trematodes identified from this group of laboratory animals.