The exopolysaccharide (EPS) "viilian" was isolated from a large-batch fermentation of Lactococcus lactis subsp. cremoris SBT 0495. After applying a newly developed purification procedure, pure viilian with a weight-averaged molar mass of 2.64 ϫ 10 3 kg/mol was obtained in a yield of 0.6 g/L culture broth. The native EPS, as well as lower molar mass fractions obtained by sonication of the native polymer, were studied by capillary viscometry and size-exclusion chromatography (SEC) coupled to multiangle laser light scattering detection (MALLS). From the viscosity data at various ionic strengths, we extracted a Mark-Houwink-Kuhn-Sakurada exponent a ϭ 0.79, and a Smidsrød B value of 0.03. By application of the Hearst, Bohdanecky ´, and Odijk models for stiff polymer coils, in connection to the experimental viscosity data, we established the characteristic ratio to be C ϱ ϭ 44 and the intrinsic persistence length q 0 ϭ 11.5 nm. The rms radii of gyration predicted from each of the models were in good agreement with the experimental radii (e.g., ͗S 2 ͘ w 1/2 ϭ 162 nm for native viilian in 0.2M NaNO 3 ), as determined by SEC-MALLS. In addition, the Odijk model predicts correct ionic strength-linear charge density dependence of the rms radius of gyration. From the combined viscosity and SEC-MALLS experiments we concluded that, in dilute aqueous solutions, viilian behaves as an intermediately stiff, random coil polyelectrolyte system.