We have examined single cell activity and field potentials in the prelimbic area of the prefrontal cortex of the rat to electrical stimulation of the CA1/subicular region of the temporal hippocampus. Excitatory unit responses were found in 50 out of 120 neurons recorded in the prelimbic area. Paired-pulse facilitation was found for both single cell responses and field potentials. High-frequency, tetanic stimulation of the temporal hippocampus produced a significant and persistent potentiation of prelimbic field potentials. The evidence suggests that the direct pathway from the temporal hippocampus to the prelimbic area of the prefrontal cortex in the rat is excitatory and can undergo long-term potentiation (LTP).