A ten-year serologic and virologic investigation into the activity of enzootic bluetongue (BT) virus was conducted in southern Texas white-tailed deer (Odocoileus virginianus texanus). Eighty-nine percent of 484 adult deer, 36% of 129 juvenile deer and 93% of 182 neonatal deer were sero-positive of BT. Antibody was not detected in fetal fawns but was found in colostrum samples. Sentinel fawn studies demonstrated that maternal antibody persists at least 8 weeks and that BT was transmitted during the fall months. The virus was isolated from a sentinel fawn but could not be recovered from deer with antibody or with organizing lesions suggestive of previous BT infection. Virus was not isolated from deer ectoparasites.