T-cell　acute　lymphoblastic　leukemia　(T-ALL)　is　an　aggressive　tumor,　in　which　T　precursor　cells　undergo　malignant　transformation,　and　the　side　effects　and　drug　resistance　of　chemotherapy　drugs　are　still　difficult　problems　hindering　the　success　of　treatment.　Vincristine　(VCR)　is　a　traditional　chemotherapy　drug　for　children　with　significant　efficacy　in　T-ALL,　but　its　side　effects　are　obvious.　Lithium　carbonate　(Li2CO3)　can　enhance　the　efficacy　of　other　chemotherapy　drugs,　but　studies　of　its　combination　with　VCR　have　not　been　reported.　The　purpose　of　this　study　is　to　investigate　the　effects　of　Li2CO3　combined　with　VCR　on　the　proliferation,　apoptosis　and　cell　cycle　of　two　pediatric　T-ALL　cell　lines,　CCRF-CEM　and　Jurkat　cells.　The　results　of　thiazolyl　blue　tetrazolium　bromide　(MTT)　colorimetric　assay　showed　that　the　viability　of　both　cells　decreased　with　the　increase　of　the　concentration　of　VCR　or　Li2CO3　alone,　which　compared　with　the　control　group　(P＜0.　05).　The　survival　rates　of　the　two　kinds　of　cells　were　different　under　the　same　Li2CO3　concentration　(P＜0.　01).　Compared　with　the　VCR　group,　the　cell　viability　and　half　maximal　inhibitory　concentration　(IC50)　values　of　Li2CO3　combined　with　VCR　group　were　reduced　in　the　two　kinds　of　cells,　and　the　coefficient　of　drug　interaction　(CDI)　between　Li2CO3　and　VCR　was　less　than　1.　Flow　cytometry　showed　Li2CO3　combined　with　VCR　group　had　the　highest　proportion　of　G2/M　and　apoptotic　cells　of　the　two　kinds　of　cells　among　the　control,　Li2CO3,　VCR　and,　Li2CO3　combined　with　VCR　group.　And　there　were　significant　differences　between　Li2CO3　combined　with　VCR　group　and　VCR　group　(P　＜　0.　05).　In　conclusion,　our　experimental　results　suggest　that　the　combination　of　Li2CO3　and　VCR　inhibits　of　T-ALL　cell　proliferation,　arrests　the　cell　cycle　in　the　G2/M　phase　and　increases　cell　apoptosis,　which　provides　a　new　experimental　basis　for　the　clinical　treatment　of　pediatric　T-ALL,　the　reduction　of　VCR　side　effects,　and　also　new　ideas　for　drug　development.　©　2024　Chinese　Society　of　Biochemistry　and　Molecular　Biology,　Peking　University.　All　rights　reserved.