Quantitative comparisons are made between calculations based on the best currently available predictive theories and experiments on the motions of rigid biomacromolecules and complexes through fluid media. Hydrodynamic properties calculated are translational diffusion coefficient, sedimentation coefficient, intrinsic viscosity, and rotational relaxation time. Structures for which calculations have been done are those representative of urease, polystyrene latex spheres with adsorbed γ‐globulin, aspartate transcarbamylase, and once‐broken rods. Conclusions are that sensitivity to structure in the hydrodynamic properties has the following order: first normal stress coefficient,Ψ1>rotationalrelaxation time,τ≫intrinsicviscosity,[η]>translationaldiffusion coefficient,DT∼sedimentationcoefficient,S20.w0;and that a model proposed by Abdel‐Khalik and Bird has good predictive capability except for structures which must be modelled by large numbers of subunits.