An existing model for volume transport in the rat proximal tubule was modified and applied to a bioartificial renal tubule. The predicted volume transport agrees well with experimental data. The volume transport model was coupled to the analytic solutions of flow in the bioartificial renal tubule bioreactor, operated in the open-shell mode with perfusion in both the lumen and surrounding shell. The results suggest that the performance of a multifiber bioreactor can be improved by controlling shell inlet conditions and fiber spacing. These results have important implications for the design and analysis not only for the bioartificial renal tubule bioreactor but also for the general case of hollow fiber bioreactors operated in the open-shell mode with perfusion in both the lumen and surrounding shell. (C) 2000 John Wiley & Sons, Inc.