The densities and viscosities were measured at 298.15 K for the quaternary system mannitol + sorbitol + sucrose + H2O and its binary and ternary subsystems (mannitol + H2O, sucrose + H2O, and sorbitol + H2O) and (mannitol + sorbitol + H2O, mannitol + sucrose + H2O, and sorbitol + sucrose + H2O). The results were used to test the applicability of simple equations for the density, kinematic viscosity, and viscosity of the multicomponent nonelectrolyte solutions. The predicted results are in good agreement with the measured values, indicating that the density, kinematic viscosity, and viscosity of the multicomponent nonelectrolyte solutions obeying the linear isopiestic relation can be related to those of their constituent binary solutions by the simple equations.