Two experiments were conducted to determine the effect of wood vinegar (WV) on the fecal microbes andgas emission in weaned pigs. In Exp. 1, 224 weaned piglets (L×Y×D, 21 d-old, initial BW 6.02 ± 0.52 kg)were assigned to four treatments of different WV levels in randomized completely block design with fourreplicates (14 piglets/pen) for 28 days, including phases I (0-2 wk) and phase II (3-4 wk). The dietarytreatments were 0, 0.1, 0.2 and 0.3% of WV added to a corn-soybean meal basal diet. The concentration ofammonia measured at 0 h and 24 h in feces did not differ among dietary treatments (p>0.05), but it waslinearly decreased (p<0.05) in 0.2% and 0.3% addition level measured at 48 h and 72 h. The concentrationof hydrogen sulfide had no significant change (p>0.05) within treatments measured at different time. The fecaltotal bacteria (TBC), Lactobacilli(LAB) and E. coli were measured on 14 d and 28 d. TBC were higher (p>0.05)in WV added treatments than the control. Similar results were obtained for LAB. But E. coli populations weredecreased (p<0.05) in treatments added WV compared to control measured on 14 d and 35 d. In Exp. 2, 288weaned piglets (L×Y×D, 21 d-old, initial BW 6.62 ± 0.31 kg) were assigned to four treatments in a randomizedcompletely block design with four replicates (18 piglets/pen) for 28 days. The dietary treatments were basaldiet (negative control, NC), 0.2% organic acid (positive control, PC), 0.2% antibiotic (AT) and 0.2% WV addedto a corn-soybean meal basal diet. The fecal total bacteria (TBC), Lactobacilli(LAB) and E. coli were measuredon 14 d and 28 d. TBC, LAB and E. coli showed lower counts in pigs fed AT diets than others. In conclusion,these results indicated that wood vinegar could reduce the NH3 concentration of feces and inhibited thegrowth of harmful bacteria.