Abstract: To investigate effects of cordycepin on learning and hippocampal neurons of mice injured by ischemia, we processed ischemic mice model by 2-vessel occlusion, and observed Y maze training of mice with post- or pre-treatment of 100 mg?kg-1 cordycepin (i.p.), which was followed by the detection of hippocampal neurons density in CA1, CA3 and DG region. The results indicated that pre-treatment of cordycepin increased rates of correct responses (RCR) and decreased trails of reaching standard (TRS) significantly (p0.05), with an increased number of hippocampal pyramidal neurons both in CA1 and CA3 region (p0.01). On the other hand, post-treatment of cordycepin remarkably reduced TRS (p0.05) without distinguished changes of RCR (p0.05) and only improved the number of pyramidal neurons in hippocampal CA3 region (p0.01) but not in CA1 region (p0.05). Together, we concluded that cordycepin conspicuously ameliorated behavioral learning of mice injured by ischemia, which was more effective with pre-treatment, possibly attributing to restoration of hippocampal neurons with cordycepin application.