The objective was to evaluate the effect of the protein and fiber levels on the greenhouse gases emission from growing-finishing pigs and determining their origin (enteric or pit). 64 growing-finishing pigs were used in 3 phases of 35 days, fed 2 levels of protein and neutral-detergent fiber in each phase. The CH₄ emission from intensive commercial raising conditions varied from 0.2 to 0.3 l/kgPV^0.75/day, which 1.3 to 25% originate from pits. The increase in fiber level caused an increase in total CH₄ emission, which was 14.6, 48 and 37% compared to normal fiber level in the first, second and third phase of study, respectively. The protein level did not change total and pit CH₄ emission, and NH₃ emission from the pits as well as the fiber level did not affect the total N₂O emission. The N₂O originated from the pits did not reach more than 1% of their total emissions.