Mesoscopic structures of poly(vinyl alcohol)-Congo red (PVA-CR) complexes in aqueous solutions were investigated in terms of dynamic light scattering (DLS) technique. The intensity-intensity time correlation function, g((2))(t), was analyzed with an equation including a single and a stretched exponential function. Two diffusion coefficients, D-f (fast) and D-s (slow) were evaluated. D-f was converted to the apparent correlation length, xi(app), via the mode-mode coupling hypothesis. The estimated xi(app) was insensitive to the sol-to-gel transition but decreased with CR concentration. This change may be related to the electrostatic screening effect. On the other hand, D-s oscillates with increasing CR concentration at a specific PVA concentration range. This explains well the reentrant sol-gel-sol-gel transition behavior observed in the PVA-CR systems. D-s seems to represent the mobility of the PVA-CR complexes, which annihilates at the gel point.