Trichuris muris is a parasitic nematode affecting mice. Following ingestion, T. muris eggs hatch in the large intestine where they develop into adults. The anterior end of the worm burrows into the lining of the gut, leaving the posterior end protruding into the lumen of the gut. The worms mate in this orientation, and the resulting eggs are released in to the gut lumen and shed faecally.

T. muris is a useful model organism for studying host parasite relationships and associated immune responses as it is closely related to the human parasite T. trichuria, known as the human whipworm, which is thought to infect a quarter of the World's population. Infection is usually asymptomatic, but can cause vitamin A deficiency in children, resulting in stunted growth and developmental delay in children. Adult worms are approximately 1 centimeter long