The optimum pH for both the rate of production and yield of hyaluronic acid (HA) by Streptococcus zooepidemicus from glucose medium was 6.7 +/- 0.2 under anaerobic conditions. High agitation rates (600 rpm) gave superior results compared to 300 rpm. Aeration of the culture (0.3 VVM) improved the HA yield, but not the rate of production and lead to some acetate and CO2 being formed, in addition to lactate and HA.