This research aimed to find preventing alternative of avian influenza (AI) disease in broiler chicken by increasing body immune. Lymphocyte T would directly react to antigen presented to the cell surface by antigen presenting cell (APC). Th-CD4 interaction functioned to maintain Th-APC bond intact during specific antigen activation. Fatty acid in virgin coconut oil (VCO) was potential as immunostimulant, which therefore could increase chicken immunity through the increase of lymphocyte T and Th-CD4. This research used 40 one-day-old broiler chickens. The method applied was Completely Randomized Factorial Design in which the first factor was two levels of vaccine, namely groups of AI vaccinated and unvaccinated. The second factor was four levels of VCO namely 0, 5, 10, 15 mL/kg feed. Day Old Chick (DOC) were divided into eight treatment groups and repeated five times. Feed and water were given ad libitum for four weeks. The result showed that the number of lymphocyte and Th-CD4 in chickens given 10 mL per kg feed and vaccinated with AI was higher than that in chickens given VCO without AI vaccine.