Abstract:The circumscription and phylogenetic relationships of Theaceae was investigated using mitochondrial matR sequences data. Phylogenetic analyses based on the matR data, strongly support a monophyletic Theoideae ( or Camellioideae) containing three wel-l supported lineages ( Stewartieae, Gordonieae and Theeae ) , but do not support the sister relationship of Theoideae and Ternstroemioideae, suggesting a paraphyletic Ternstroemioideae. These results are consistent with some recent authors recognizing Theaceae sensu stricto ( s1s. ) to the ex clusion of Ternstroemioideae, and give further support for the three-tribe class-ification system of Theaceae s1s. of Prince and Parks in 2001. On the other hand, the matR-based analyses provide a better resolution of the phylogeny within Theaceae s1s. , i1 e. , Stewartieae is the basalmost lineage in Theaceae, and Theeae and Gordonieae are closely related with weak support ( bootstrap= 64%) .