The regulated Cl secretory apparatus of T84 cells responds to several pharmacological agents via different second messengers (Ca²⁺, cAMP, cGMP). However, information about water movements in T84 cells has not been available. In the absence of osmotic or chemical gradient, we observed a net secretory transepithelial volume flux (J_w = 0.16 ± 0.02 µl · min¹ · cm²) in parallel with moderate short-circuit current values (I_sc = 1.55 ± 0.23 µA/cm²). The secretory J_w reversibly reverted to an absorptive value when A-23187 was added to the serosal bath. Vasoactive intestinal polypeptide increased I_sc, but, unexpectedly, J_w was not affected. Bumetanide, an inhibitor of basolateral Na⁺-K⁺-2Cl cotransporter, completely blocked secretory J_w with no change in I_sc. Conversely, serosal forskolin increased I_sc, but J_w switched from secretory to absorptive values. Escherichia coli heat-stable enterotoxin increased secretory J_w and I_sc. No difference between the absorptive and secretory unidirectional Cl fluxes was observed in basal conditions, but after STa stimulation, a significant net secretory Cl flux developed. We conclude that, under these conditions, the presence of secretory or absorptive J_w values cannot be shown by I_sc and ion flux studies. Furthermore, RT-PCR experiments indicate that aquaporins were not expressed in T84 cells. The molecular pathway for water secretion appears to be transcellular, moving through the lipid bilayer or, as recently proposed, through water-solute cotransporters.