The purpose of this paper is to draw a general picture for viscometric behaviour of polyelectrolytes. The polymers tested are hyaluronan (lambda = 0.7) and sodium polystyrene sulfonate (lambda = 2.8) with different molecular weights. The viscometric behaviour in isoionic dilution is examined and one demonstrates that k＇[eta]similar to C-s(3/2). Dilution in water or with solvent of low salt concentration causes the reduced viscosity to pass through a maximum for a given polymer concentration. The position of the maximum and the amplitude of this maximum is analyzed for the low molecular weight samples in the dilute regime. The electrostatic contribution dominates and the treatment adopted gives good agreement between calculated and experimental data.