The theory of White and Sub of transversely isotropic plastic viscoelastic fluids is re-visited. A transversely isotropic yield surface developed by Spencer to represent plastic flow in fiber re-inforced composites is proposed as a replacement for Hill＇s anisotropic yield condition in the theory. The two yield surfaces are compared and interpreted for different applied stress fields. A new expression for the constitutive equation essentially explicit in the deviatoric stress tensor has been developed.