ABSTRACT: The aim of this study was to explore the effects of bamboo vinegar powder on growth performance, diarrhea situation and mRNA expression levels of cytokines i.e., interleukin-10 (IL-10), interleukin-22 (IL-22), and interleukin-25 (IL-25) in immune organs of weaned piglets, and to accumulate theoretical data for the application of bamboo vinegar powder in weaned piglet production. Forty-five crossbred (Duroc × Landrace × Yorkshire, all male) weaned piglets with similar body weight (6.74 ± 0.17 kg) at 31 days of age were randomly assigned to 5 treatments with 3 replicates per treatment and 3 piglets in each replicate. The five treatments were as follows: CON (a basal diet), ANT (the basal diet + 0.12% antibiotics), BV1 (the basal diet + 0.1% bamboo vinegar powder), BV5 (the basal diet + 0.5% bamboo vinegar powder), BV10 (the basal diet + 1.0% bamboo vinegar powder). This experiment lasted 35 days. The growth performance and diarrhea situation were recorded. The relative mRNA expression levels of IL-10, IL-22 and IL-25 in liver, spleen, duodenum and mesenteric lymph nodes were detected by real-time PCR. Feed: gain of BV5 was significantly lower than that of CON (P < 0.05). In comparison with CON, diarrhea rate and diarrhea index of BV1 and BV5 all tended to decrease (P < 0.1). Compared with CON, mRNA expression level of IL-10 in liver of ANT tended to be lower (P < 0.1) and these of BV1, BV5 and BV10 were significantly reduced (P < 0.05). The mRNA expression levels of IL-10 in duodenum of ANT, BV1, BV5 and BV10 were all lower than those of CON, of which BV10 had significantly decreased IL-10 mRNA expression in duodenum (P < 0.05). The mRNA expression levels of IL-22 in duodenum of ANT, BV1, BV5 and BV10 all tended to be inhibited compared with CON (P < 0.1). With the increase of bamboo vinegar powder dosage, mRNA expression levels of IL-25 in spleen and mesenteric lymph nodes of BV1, BV5 and BV10 tended to be up-regulated. Overall, bamboo vinegar powder could improve growth performance, and regulate mRNA expression levels of IL-10, IL-22 and IL-25 in immune organs of weaned piglets. The dosage at 0.5% showed optimum effects.