Two experiments were conducted to determine the role of the turkey hen’s immune system in the so-called seasonal decline in fertility. Results from Experiment I demonstrated that trauma to the oviduct induced either at the time of the initial artificial insemination, or during subsequent inseminations had no effect upon hen fertility, or serum anti-sperm antibody titers. No differences in fertility were found between hens showing a positive or negative anti-sperm antibody response. Experiment II demonstrated that only relatively infertile turkey hens had antibody positive cells within the uterovaginal sperm storage gland epithelium (UVSG), while fertile turkey hens had no such cells. Antibody positive amorphous material was found within the lumen of the UVSG of relatively infertile, but not fertile turkey hens. Blood serum from relatively infertile hens showed minimal anti-sperm antibody titers. It was concluded that the seasonal decline in fertility in turkey hens is a local not due to a humoral immune response against spermatozoa. However, immune response against spermatozoa appears to exist in the uterovaginal sperm storage glands of the turkey hen, which has a detrimental effect upon fertility / Master of Science