The aim of this study was to investigate the functional expression of cystic fibrosis transmembrane conductance regulator (CFFR) with electrophysiological and molecular technique in rat oviduct epithelium. In whole-cell patch clamp,oviduct epithelial cells responded to 100 μM 8-bromo-adenosine 3’,5’-cycfic monophosphate (8-Br-cAMP) with a rise in inward current in Gap-free mode, which was inhibited successively by 5 μM CFTR(inh)-172, a CFTR specific inhibitor, and 1 mM diphenylamine-2-carboxylate (DPC), the CI- channel blocker. The cAMP-activated current exhibited a linear current-voltage (I-V) relationship and time- and voltage-independent characteristics. The reversal potentials of the cAMP-activated currents in symmetrical CI- solutions were close to the CI- equilibrium, 0.5±0.2 mV (n=4). When CI- concentration in the bath solution was changed from 140mM to 70 mM and a pipette solution containing 140 mM CI-was used, the reversal potential shifted to a value close to the new equilibrium for Ci-, 20±0.6 mV (n=4), as compared with the theoretic value of 18.7 mV. In addition, mRNA expression of CFTR was also detected in rat oviduct epithelium. West blot analysis showed that CFTR protein is found in the oviduct throughout the cycle with maximal expression at estrus, and immunofluorescence and immunohistochemistry analysis revealed that CFYR is located at the apical membrane of the epithelial cells. These results showed that the cAMP-activatod CI- current in the oviduct epithelium was characteristic of CFTR, which provided direct evidence for the functional expression of CFTR in the rat oviduct epithelium. CFTR may play a role in modulating fluid transport in the oviduct.