Objective: To study the effects of chronic lithium on N-methyl-d-aspartate receptor subunit 2B (NR2B) tyrosine phosphorylation and the interactions of NR2B and PSD-95 with Src induced by cerebral ischemia/reperfusion (I/R). Methods: Transient (15 min) cerebral ischemia was induced by four-vessel occlusion procedure in SD rats. Immunoprecipitation (IP) and immunoblotting (IB)were performed to investigate the phosphorylation and interactions of proteins. The effects of lithium on tyrosine phosphorylation of NR2B and its interactions with PSD-95 and Src were examined. Results: Transient cerebral ischemia 15 min followed by reperfusion 6 h (I/R 6h) caused a significant increase in tyrosine phosphorylation of NR2B. Administration of LiCl for 7days before ischemia caused a profound decrease in tyrosine phosphorylation of NR2B. Similiarly, the interactions of NR2B and PSD-95 with Src were also enhanced by I/R 6 h.moreover, these interactions were also inhibited by chronic lithium. Conclusion: Pretreatment with lithium decrease tyrosine phosphorylation of NR2B and interactions of NR2B and PSD-95 with Src during cerebral I/R.