Abstract: Plumbagin (Plumbago zeylanica L.) has a wide spectrum of anticancer activity with a relatively lower toxicity. The molecular mechanisms of proliferation inhibition and apoptosis induction by plumbagin on esophageal squamous carcinoma cell lines may be important for the structure modification and clinical application of plumbagin. After treatment of KYSE-30, KYSE-70 and KYSE-140 cells with 0-20 μmol·L^-1 of plumbagin for 24, 48, 72 h, CCK8 was used to examine the proliferation, Annexin V and PI immunofluorescence staining for apoptosis, real-time PCR and Western blot for FoxM1 mRNA and protein expression, dual-luciferase reporter gene assay for the transcriptional activity of FoxM1, respectively. In addition, the relationship between anti- tumor effect of plumbagin and FoxM1 was investigated in vivo. Plumbagin significantly inhibited proliferation and induced apoptosis of esophageal squamous carcinoma cell in vitro and in vivo. Moreover, plumbagin down-regulated the expression of FoxM1 through suppression of its gene transcription. Our findings suggest that plumbagin may inhibit the proliferation of esophageal squamous carcinoma cell in vivo and in vitro through down-regulating the expression of FoxM1.