Objective To investigate whether there is a crucial period for focal low frequency stimulation (LFS) inhibiting the development of amygdala-kindling in rats.Methods The effect of focal LFS (1 Hz, 15 min) applied in different periods of the kindling development process were investigated.LFS was initiated immediately after daily kindling stimulation.Results LFS given in the first week of kindling or during the whole kindling process had similar antiepileptic effect on the development of kindling, indicated by the slowed development of seizure stage and the shortened afterdischarge duration, while LFS applied after the first week of kindling had no effect, even aggravated aflerdischarge duration.All the rats in the control group or received LFS after the first week were fully kindled within 20 d.However, only 44% rats received LFS in the first week and 32.5% rats received LFS during the whole kindling process were fully kindled within 20 d.Conclusion The first week of kindling process is a crucial period for focal LFS inhibiting the development of amygdala-kindling.The early period in epileptogenesis may be an ideal time for LFS treatment.