Gastrointestinal nematode parasites undergo several developmental stages within their mammalian host, each presenting different antigenic challenges to the immune system. To examine the expression of different immune mediators over time, biopsy samples were collected from the cannulated abomasum (true stomach) of immune sheep at several times after a challenge infection with Haemonchus contortus L3s. IL-5 and IL-13 mRNA expression levels were significantly increased above saline-challenged control levels at 5 and 7days post challenge, while IL-4 showed an earlier peak at day 2 post challenge. IL-5, IL-13 and IL-4, as well as IFN-I? mRNA levels, peaked at 7days before decreasing to non-significant levels at 28days post challenge. TNF-I? followed a similar profile while there was a slight increase in TGF-I? in both control and challenged sheep. There was a significant increase in galectin-14 mRNA in the L3 challenged compared with the saline challenged group at 7days while both galectin-11 protein and mRNA levels increased significantly by day 3 post challenge, peaking at 5-7days post challenge. Distinct correlations were observed between these immune parameters at different times after L3 challenge. The galectin-14 protein level at day 2 post challenge was the only measured mediator significantly negatively correlated with worm burden. These studies highlight the dynamic nature of the immune response during parasite infection and the need to consider the different life cycle stages involved.