The northern fowl mite (Ornithonyssus sylviarum) is a cosmopolitan ectoparasite of birds and serious pest of poultry in North America. The chicken is capable of acquiring resistance to northern fowl mite and develops mite-specific antibodies over the course of an infestation. However, the importance of antibodies to mite resistance and the function of cellular components in the immune response remain unknown. Additionally, details of mite population dynamics, including population size and age structure, are not known. This experiment evaluated the complete immune response of the host and correlated the parameters of host immunity with mite population dynamics over the course of an infestation. Chickens infested uniformly with northern fowl mite were monitored with regular visual mite population estimates and host blood collection. Peripheral blood samples were analyzed for mite-specific IgG and IgM immunoglobulins using ELISA and cell types (monocytes, lymphocytes, granulocytes) were quantified from thin blood smears. Chickens were destructively sampled at set intervals and the entire mite population from each host was removed to count the absolute size and age structure. Skin samples from mite feeding sites were taken from each host for histological examination of skin inflammation. Cell types and structural features of the skin were characterized using hematoxylin and eosin staining. T-lymphocytes (CD4+ and CD8+) were quantified using antibody labeling.