Abstract: Dipterocarpoideae is a species-rich subfamily of Dipterocarpaceae. Dipterocarpaceae in Thailand is represented by 65 species in 8 genera. In recent years molecular taxonomist constructed a phylogenetic tree of dipterocarps found in South-East Asia. However, many species of dipterocarps found in Thailand are not included on that tree. In an effort to complete the tree, the phylogenetic relationships among 23 species belonging to 7 genera of dipterocarps found in Thailand were studies using nucleotide sequences of two intergenic spacer region between trnL-trnF and atpB-rbcL in chloroplast DNA. With Neobalanocarpus heimii as an out group, the molecular tree was consistent with the morphological classification and it was clearly resolved two major groups; Vavate-dipterocarpi and Imbricate-Shorea. The analysis showed that each member genera have similar characteristics and base chromosome number of 11 and 7, respectively. The first group consisted of genus Diptercarpus, Anisoptera, Cotylelobium and Vatica. Shorea and Hopea were in the second group.