A new species of the important timber tree family Dipterocarpaceae, Hopea macrocarpa Poopath & Sookch., from Hala-Bala forest, Narathiwat, Thailand is described and illustrated. Hopea macrocarpa is morphologically similar to H. mengarawan Miq. from Peninsular Malaysia, Sumatra and Borneo in its leaf shape, leaf size, leaf blade texture and number of secondary nerves. The new species differs from H. mengarawan, however, by having bigger flower buds, bigger fruits and longer fruit stalks