Background: Oral cancer is a health problem in Thailand. Cratoxylum formosum subsp. pruniflorumGogel (Teawdang), normally consumed in northeast Thailand, has proven cytotoxic to cervical cancer celllines including HeLa, SiHa and C-33A. Recently, Asian oral cancer cell lines, ORL-48 and ORL-136, wereestablished. Therefore, we aimed to study cytotoxicity of Teawdang in these. Total phenolic (TPC) and flavonoidcontent (TFC), and antioxidant activity of Teawdang were also determined. Materials and Methods: Teawdangwas purchased from Khon Kaen market during June-October 2013. Hexane (CHE), ethyl acetate (CEE) andmethanol (CME) extracts of its edible part were analyzed for TPC by the folin-ciocalteau method and for TFCby an aluminium colorimetric method. Antioxidant activity and cytotoxicity in normal Vero cells and oral cancercells were investigated. Cell viability was assessed using 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazoliumbromide (MTT) assays. Results: CME and CEE had higher TPC and TFC and antioxidant activity than CHE.Both CME and CEE, at 200 μg dry wt/mL, were cytotoxic to the studied oral cancer cell lines. However, CMEwas cytotoxic to Vero cells whereas CEE was not. Compared to Vero cells, CEE significantly inhibited ORL-48and ORL-136 growth (p=0.03 and p=0.02, respectively). Conclusions: CEE exhibited cytotoxic effects on thestudied oral cancer cell lines but not normal Vero cells. The bioactive compounds in CEE should be furtherpurified and elucidated for their mechanisms of action for development as anticancer agents.