Zero-shear viscosities eta(0) of tetrahydrofuran solutions of cellulose tris(phenyl carbamate) (CTC), a moderately stiff polymer of persistence length q = 10.5 nm, were measured as a function of the polymer concentration c and molecular weight M. The molecular weight dependence of eta(0) at high concentration is definitely stronger than that of flexible polymers, reflecting the chain stiffness of CTC. The eta(0) data for higher molecular weight samples are favorably compared with the fuzzy-cylinder model theory, but it is necessary to consider up to the terms in C-2 in the intermolecular hydrodynamic interaction (HI) when the M of CTC is low. When compared among polymers of the same contour length but different stiffness, the intermolecular HI becomes more important with decreasing q.