The biosynthesis of lovastatin, a cholesterol lowering agent formed by the filamentous fungus Aspergillus terreus, was examined in a 2.5 L jar fermenter. In batch bioreactor cultures conducted at various agitation rates, 400 rpm showed the best result in terms of lovastatin production. Notably, the effect of pH on lovastatin biosynthesis was found to be significant: when the pH was controlled at around 5.8 during the whole fermentation period, lovastatin concentration reached 598 mg/L, which is much hihger than the amounts obtained by pH-uncontrolled and pH 7.4-controlled fermentations. In addition, both L-histidine and L-tryptophan were observed to be favorable amino acids for the enhancement of lovastatin production when 6 g/L of the respective amino acids were supplemented at the beginning of the fermentation period. By further optimization of the production media and the physical environment, lovastatin production was increased to 836 mg/L (3.5 mg/L/hr) which is approximately 10 times higher than the productivity of the basic control culture.