Abstract： Objective　To test the hypothesis that neuronal cdc2-like kinase (Cdk5/p35nck5a) plays an important role in neuronal maturation and sprouting.Methods　Changes kinase activity, expression levels and subcellular localizations of Cdk5 and p35nck5a in the rat hippocampus were studied during kindling progression by Western blot analysis, immunohistochemitry, immunoprecipitation and kinase assay. Results　Kinase activity in kindling rats was significantly higher than that in normal adult rats. The kinase activity at stage 3 was most prominent among all stages of kindling progression. The changes in kinase activity coincided with those of p35nck5a expression in kindling rats. In contrast, the expression of Cdk5 was constant throughout the progression of kindling stages. However, subcellular localization of Cdk5 dramatically changed in the hippocampal neurons of kindling rats. Cdk5 was translocated from axon to soma when kinase activity was high. p35nck5a was always localized in the soma throughout kindling progression.Conclusions　Neuronal cdc2-like kinase plays an important role in synaptic reorganization, and the translocation of Cdk5 to the soma from the axon may be a novel regulatory mechanism to control kinase activity.