The interactions of polymerized surfactants and hydrophobically modified ethyl hydroxyethyl cellulose (HMEHEC) have been investigated in terms of their viscosities. Three polymerizable surfactants used were sodium 10-undecenoate (SUD), sodium 11-(N-ethylacrylamido)undecanoate (SEAAU), and zwitterionic (((acryloyloxy)undecyl)dimethylammonio)a (AUMAA). These polysoaps exerted varying degrees of hydrophobic interactions with HMEHEC via the formation of mixed micelles as clusters of physical crosslinks. Polymerized SEAAU showed a 27-fold increase in the viscosity of the mixed system, but the effect was much inferior for the other two systems. The copolymers of the surfactants and styrene also interacted rather strongly with HMEHEC. The dominating effect of electrostatic charges on the viscosity is demonstrated by the marked difference between the system with negatively charged poly(SEAAU) and that with the charge-neutral poly(AUMAA).