The adsorption of a flexible polymer from a good solvent onto a rigid cylindrical rod has been investigated by model calculations using heterogeneous lattice theory. The excess adsorbed amount per unit surface area (Gamma(ex)), the. concentration of the adsorbed polymer at the rod surface (phi(1)), and the excess surface free energy (A(d)egrees) have been studied, for various choices of rod radius (R = 0.5-10 lattice layers), polymer length (r(p) = 10-500 segments), and excess polymer-surface interaction (Delta(chi) drop (chi polymer,surface) - (chi solvent,surface)). For R exceeding a few lattice layers, all effects of surface curvature are weak, and the adsorption characteristics are close to those found for a flat surface. For very thin rods, phi(1) decreases significantly with decreasing R, especially for moderately attractive Delta(chi). This effect is attributed to the decrease in adsorption energy (at constant Delta(chi)) for decreasing R. In contrast, Gamma(ex) may either increase or decrease with decreasing R, depending on Delta(chi) and r(p). For weakly anchored polymers (weak attraction or short polymers), the effect of the decreased adsorption energy for small radii dominates, leading to a decrease in Gamma(ex) for decreasing R. For strongly anchored polymers (strong attraction or long polymers), however, Gamma(ex) is larger for smaller R, owing to the larger accessible volume per surface area for nonadsorbed polymer segments. The implications of the results for the mixed association of flexible and rodlike polymers, as observed experimentally in certain gelling polysaccharide mixtures, are discussed.