The viscosity measurements of four Carbopol solutions at various temperatures and concentrations show shear thinning effects. However, an unexpected viscosity-temperature behavior according to the concentrations of Carbopol solutions has been found. The viscosities of 3500 and 5000 wppm of Carbopol solutions decreased with increasing temperature. However, the viscosities of the 7500 and 10 000 wppm solutions increased with increasing temperature.