The viscoelastic properties of a well-characterized exocellular polysaccharide (EPS) produced by the lactic acid bacterium Lactococcus lactis subsp. cremoris strain B40 were investigated. Dynamic theological measurements were made as a function of frequency and EPS concentration. The bead-spring model of Rouse could reasonably describe the dynamic properties. Concentrated EPS solutions have a significant elasticity (G ' > G ") at high frequencies. The relatively high G ' values at high concentrations and high frequencies are indicative of significant normal stress differences, and we put forward a hypothesis that suggests that these normal stresses may explain the contribution of EPSs to the ropy behavior of yogurts.