Tracer dispersion in polysaccharide (scleroglucan) solutions flowing thorugh 0.56-mm-ID capillary tubes was studied experimentally. In contrast with expt experiments modeling enhanced recovery processes, the polymer concentration remains constant during a given experiment, while the tracer concentration varies. A preparation procedure giving stable theological characteristics is described, as well as their dependence on the polymer concentration C-p (100 mg/L less than or equal to C-p less than or equal to 2,000 mg/L). Dispersion measurements are performed with ionic tracers at Peclet numbers between 100 and 2,000. Dispersion coefficient K increases as the square of the Peclet number, showing that the Taylor dispersion mechanism remains dominant. At a constant flow velocity, K decreases by about 75% when C-p increases from 0 to 2,000 mg/L. This variation is related to the flattening of the velocity profile and can be predicted both with a power-law theological model and Monte Carlo simulations. The extension of these measurements to heterogeneous porous media is discussed.