The hoatzin is a folivorous bird with microbial fermentation in the crop that consumes plants that contain saponins. We investigated detoxification activity of saponins by bacteria from the hoatzin crop, and how this activity was affected in the presence of methanogens. Strains and mixed cultures were grown in presence of 200 μg·ml^-1 Quillaja saponins. Detoxification was determined as loss of haemolytic activity. The methanogenesis was inhibited added bromoethanesulphonic acid (BES). Mixed cultures showed higher rate of saponin detoxification than strains and it was reduced by BES. The hoatzin bacteria detoxify saponins, and methanogenic Archaea might act as a hydrogen sink.