An aerobic, Gram-negative bacterial isolate, strain DX5-10T, was isolated from coastal sediment of the East China Sea. The taxonomy of strain DX5-10T was studied by phenotypic and phylogenetic methods. Strain DX5-10T was motile, formed faint-yellowish colonies and was positive for catalase reaction and weakly positive for oxidase reaction. The nearly complete 16S rRNA gene of strain DX5-10T was obtained and sequence analysis indicated that strain DX5-10T represented an independent lineage within the Roseobacter clade of Alphaproteobacteria. Strain DX5-10T was phylogenetically related to members of the genera Roseobacter, Loktanella, Roseisalinus, Silicibacter, Antarctobacter, Sulfitobacter, Salipiger, Ruegeria and Roseivivax, and the sequence identities among them were less than 95.0%. The predominant respiratory ubiquinone of strain DX5-10T was Q-10 and the DNA G + C content of strain DX5-10T was 63.3 mol%. Therefore, strain DX5-10T represents a novel species of a novel genus, for which the name Yangia pacifica gen. nov., sp. nov. is proposed, with the type strain DX5-10T (= CGMCC 1.3455T = JCM 12573T).