This paper describes an experimental study of the effect of urea on micellar properties of aqueous solutions of Triton X-100. The increase of critical micelle concentration of the surfactant as urea rises has been monitored by changes in pyrene 1:3 ratio as a result of the microenvironment modifications induced by micellation. Quenching on fluorescent probe by neutrals and ionic quenchers provides information about the changes in the permeability of the micelle with the urea addition. From fluorescence polarization measurements using both hydrophobic (2-methylanthracene) and hydrophilic (rhodamine B) probes, we obtain useful information about structural changes induced by urea in Triton X-100 micelles. The proposed mechanism of urea action is also supported by the changes promoted by urea addition in the cloud point of the surfactant.