The objective of this study was to evaluate the effect of dietary supplementation of a Rubus coreanus ethanolic extract on immunostimulatory response in white leg shrimp Penaeus vannamei. Shrimps with an average initial weight of 0.5 ± 0.04 g were collected and acclimatized for 10 days. Four experimental diets including a control diet, a probiotic diet and 0.25 and 0.5% of R. coreanus ethanolic extract (RcEE) diets were used to feed the shrimps. After 8 weeks of culture, shrimp fed with probiotic and 0.25% RcEE diet had showed significant enhancement in the growth while shrimp fed with 0.5% RcEE diet showed significantly increased expression of immune genes and antioxidant enzymes activities. One week of challenge experiments for all the four diets fed shrimps showed decreased cumulative mortality in the 0.5% RcEE diets fed shrimps, when compared with the probiotic and 0.25% RcEE diet fed shrimp groups. The results indicates that R. coreanus ethanolic extract could be used as a herbal immunostimulant for shrimps to increase its immunity and disease resistance against the bacterial pathogen, Vibrio alginolyticus.