This study was performed to evaluate effects of dietary supplementation organic medicinal charcoal (OMC: Olga Black) on aflatoxin adsorption capacity, digestibility, population of Lactobacillus and E. coli of feces and the fecal odor emission by in vitro and in vivo in finishing pig diet. Exp 1. the aflatoxin adsorption capacity of OMC, pyroligneous charcoal (PC), and coconut tree charcoal (CC) was measured using the ELISA test kit. The aflatoxin absorption capacity was 100, 10 and 20% in OMC, PL and CC, respectively (P < 0.05). The effects of OMC on digestibility of dry- and organic matter were evaluated by in vitro prediction methods (Boisen, 1991). Treatments of in vitro and in vivo included: 1) CON (basal diet contaminated with 1,543ppb of deoxynivalenol and 596ppb of zearalenone); 2) OMC (basal diet + 0.25% Olga Black; 3) PC (basal diet + 0.50% Pyroligneous Charcoal); 4) CC (basal diet + 0.50% Coconut tree Charcoal). The digestibility of OMC on dry matter was significantly higher than CON, PC, and CC (P < 0.05). The digestibility of OMC on organic matter was significantly higher than CON (P < 0.05). Exp 2. a 10-d trial with 20 [(Yorkshire × Landrace) × Duroc)] finishing pigs (BW = 81 ± 3.3 kg) was conducted to investigate the population of Lactobacillus and E. coli in feces, and the fecal odor (NH₃, H₂S, total mercaptans, and acetic acid) in vivo. The fecal NH₃ and H₂S emissions of OMC were significantly lower than CON, PC, and CC (P < 0.05). Several Lactobacillus in feces of OMC and CC were significantly higher than CON and PC (P < 0.05). Several fecal E.coli of OMC and CC were lower than CON and PC (P < 0.05). It was thought that organic medicinal charcoal is useful as a feed additive in pig diets because it improves the digestibility of feed and the fecal odor, and has positive effect on the population of microorganism in feces.