Repeated injection of an initially subconvulsive dose of cAMP into the rat amygdala (AM) produced progressive seizure development similar to that of electrical kindling. The chemical kindling occurred in a dose-dependent manner. Furthermore, when cAMP was combined with EDTA, a strong inhibitor of cAMP phosphodiesterase, the seizure development was remarkably facilitated. When the animals that had been chemically kindled were subjected to electrical kindling, they rapidly developed seizures. These results, together with those previously published, suggest that cAMP participates in the seizure development induced by AM kindling.