Intestinal parasitic infection is still a major problem in humans and animals, yet host immunity against gut parasitic infection remains partially understood. Eosinophilia and mastocytosis are features of such infection that have been shown to be genetically controlled. The expression of IL-6 is detected in eosinophils, mast cells and neutrophils and may be responsible for the regulation of leucocytes at infective sites. The relationships between IL-6 expression, eosinophilia, mastocytosis and host immunity remain unclear. In the present report, a close correlation between IL-6 mRNA+ cells, eosinophilia, mastocytosis and worm expulsion is demonstrated, which may indicate a role for IL-6 in regulation of host immunity against intestinal parasite infection.