This study was conducted to determine the effects of dietary probiotics Biopowder^R (BP) on pigperformance, carcass characteristics and ammonia concentration in feces. A feeding trial was conducted witha total of 36 growing pigs of an average 29kg body weight. Each treatment had 4 pigs with 3 replications.Pig during grower (26days) and finisher periods (62days) were fed 0.15 and 0.30% concentrations of BPrespectively. Body weight gain slightly increased for pigs fed BP during overall periods compared withcontrol, not significantly different. Especially, in growing periods, the body weight gain of BP treatmentincreased by 10% compared with control (700g vs 775g), in finishing periods, that of BP 0.3% treatmentincreased by 10% compared with control (890g vs 980g), not significantly different among treatments. Feedintake slightly increased for pigs fed BP in overall periods. During grower periods, the feed intake of BP0.3% treatment increased by 11.0% more than control, but also not significantly different among treatments.Feed efficiency was slightly improved for pigs fed BP overall periods when compare to the control, butnot significantly different among treatments. In feces, average ammonia concentration (ppm) and bacterialcount (log cfu/g) were not affected by BP addition. There was no significantly different in carcass weight,fat thickness and carcass grade. In conclusion, supplemental BP tended to slightly improve the performanceof pig and did not influenced the concentration of ammonia in feces and carcass characteristics.