An understanding of amount of the sulphur and pyridoxine required for growth of ruminal bacteria is of importance for optimizing ruminal microbial protein and total sulphure amino acids synthesis. Whereas the results of some experiments indicate that sulphur and water soluble B vitamin stimulate growth of rumen bacteria in vitro condition. For example, Cho et al. (1988) reported average microbial protein yields were 35.14, 37.67, 36.02 and 36.07 mg/100ml, respectively, with control, and N:S ratio of 10:1, 15:1 and 20:1, and higher in rumen fluid containing S than the control. The objective of this experiment was to determine the effect of different level of S and B6 on ruminal microbial protein synthesis.