Welan, purified as its sodium salt from unpasteurised culture broth, was analyzed by dilute aqueous viscometry. Measurements in water and at low ionic strength were carried out to evaluate the charge effect on intrinsic viscosity. The value of intrinsic viscosity at low ionic strength, determined by the isoionic dilution method, is close to that obtained at higher salt concentrations. A comparison is made among the stiffness parameters determined by different treatment of experimental data The results agree with previous reports on the weak polyelectrolyte character and high stiffness of the welan chain.