The experiment aimed at assessing the effect of supplementation of microbial products on the gas production and the concentrations of NH3 and H2S in feces of pigs under anaerobic condition, was conducted Sealed plastic jars (1.000 ml capacity) containing pig feces with/without microbial product were allocated in a completely randomized design with five treatments and 3 replicates. Five treatments were: 1) ĐC (Control): No microbial product; (2) KM1: microbial product 1 at 0,5 g/100 g pig feces; (3) KM2: microbial product 2 at 0,5 g/100 g pig feces; (4) Yucca: microbial product (KMPC-CT3) at 0,5 ml/100 g pig feces and (5) Trico: microbial product containing Trichoderma spp. at 0,5 g/100 g pig feces. Results of the experiment showed that incubated pig manure under anaerobic conditions gave a higher OM and total N in the treatments with supplement of microbial product compared to these of control treatment. From 7 to 10 days after incubation, the amount of gas was slowly reduced and up to 10 days, the control treatment (ĐC) had the highest gas volume (615.0 ml) and the lowest was in KM2 (545 ml). However, this difference was not statistically significant (P>0,05). For concentration of NH3 (ml), at 10 days after incubation, the control treatment (ĐC) had the highest NH3 concentration (10.75) and the lowest was the KM2 (4.25) (P