Rumen fermentation, and rumen fluid dilution rate as influenced by 75% (75C) or 25% (25C) concentrate diets fed at the same level of energy intake was studied with four steers. Rumen pH was lower (P < 0.05) in steers fed 75C. Liquid flow rate and liquid turnover time were increased (P < 0.05) by feeding 25C. Key words: Liquid dilution rate, fermentation, concentrate level