We studied the effect of cyclic guanosine 3',5'-monophosphate (cyclic GMP) on p-aminohippurate (PAH) uptake by basolateral membrane vesicles isolated from rat kidney cortex. Cyclic GMP inhibited PAH uptake dose-dependently. Dibutyryl cyclic GMP inhibited the uptake of PAH to the same extent. However, cyclic adenosine 3',5'-monophosphate, cyclic cytidine 3',5'-monophosphate and guanosine monophosphate had no effect on PAH uptake by membrane vesicles. Therefore, the inhibition of PAH uptake was specific to cyclic GMP and not common to nucleotides. In the presence of probenecid, an inhibitor of PAH transport, cyclic GMP did not affect PAH uptake. Thus, cyclic GMP had an inhibitory effect on probenecid-sensitive PAH transport. Inhibition by cyclic GMP of PAH uptake by basolateral membrane vesicles as described this study may contribute to the decrease in PAH accumulation in kidney cortical slices caused by the cyclic nucleotide which we previously reported.