We provide experimental demonstration that the spread of tracer elements in a tank containing a viscoelastic liquid and agitated by a submerged jet pointing to the base of the tank can be influenced by the relaxation time of the liquid. We analyzed the temporal spreading of the boundary of a tracer-front in two dimensions using flow visualization at early stages and found that for a given fluid, the evolution of the tracer-front at various injection velocities follows a universal trajectory when considered on a normalized time scale of , where t is observation time, vN is injection velocity and is the effective diffusivity of the tracer elements in the medium. For a different fluid, at a given , the trajectory scales with the relaxation time of the fluid. The importance of relaxation time to the evolution of a tracer-front is something previously unreported. (c) 2017 American Institute of Chemical Engineers AIChE J, 63: 3132-3140, 2017