Saccharomyces boulardii is non-pathogenic probiotic yeast with many health benefits. In the present work, studies were carried out to improve cell growth kinetics to produce cell mass of this biotherapeutic yeast in semi-industrial scale. At first, five different media were screened to select the most appropriate formula for biomass production. The medium which yielded highest cell mass of 2.57 g L-1 and lowest ethanol was selected and further optimized by changing the concentrations of each component. The optimized medium composed of (g L-1): Glucose, 20; Corn steep liquor, 15; NaNO3, 1.0; KH2PO4, 6.0; MgSO4.7H20, 3.0; CuSO4.5H20, 0.002; FeSO4.7H20, 0.001; ZnSO4.7H20, 0.01 was then used for yeast biomass production in a pilot scale 16-L bioreactor in batch culture under controlled and uncontrolled pH. The highest biomass of 8.2 g L-1 was achieved in pH controlled culture. This was almost double of the biomass obtained in shake flask. In conclusion, production process has been developed for high cell mass production of the biotherapeutic yeast S. boulardii in semi-industrial scale.