Two theories have been compared for the prediction of the effective viscosities of laminates made up of layers of oriented discontinuous fiber assemblies suspended in a viscous fluid. In the first theory, the layers are constrained to exhibit identical strain-rate components, while in the second theory the individual layers are assumed to be unconstrained by one another. Results are presented for four typical laminates and for material properties of a highly anisotropic assembly. These results indicate that the properties presented for the constrained condition equal or exceed those predicted for the unconstrained theory in all cases.