The infectivity of turkey hemorrhagic enteritis (HE) virus was studied in poults with no detectable maternal antibody and in turkeys bursectomized or injected with killed-virus preparations. Poults less than three weeks old were not infected by hemorrhagic enteritis virus, and survivors were susceptible to challenge at the age of eight weeks. Three- and four-week-old poults were susceptible to HE, and survivors resisted challenge. Bursectomy partially interfered with the immune response but did not alter the course of the disease, and survivors were resistant to challenge. Injections of spleen suspension containing 1% formalin produced antibody in only two of six turkeys. Three of the four poults without detectable antibody resisted challenge.