A novel yellow-pigmented actinobacterium was isolated from seawater collected from Hwasun Beach in Jeju, Republic of Korea. A comparative analysis of the 16S rRNA gene sequence indicated that the organism, designated HFW-26(T), was closely related to members of the genus Brevibacterium. As found for other species of the genus Brevibacterium, strain HFW-26(T) possessed meso-diaminopimelic acid as the diagnostic cell-wall diamino acid, contained MK-8(H(2)) as the major menaquinone, contained polar lipids that included diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and an unknown phospholipid, and had anteiso-C(15 : 0) and anteiso-C(17 : 0) as the predominant fatty acids. The G+C content of the DNA was 71.4 mol%. The phylogenetically closest relative was Brevibacterium picturae DSM 16132(T) (99.0 % 16S rRNA gene sequence similarity). However, DNA-DNA hybridization of strain HFW-26(T) showed 35.1-43.7 % relatedness with respect to B. picturae DSM 16132(T). The novel isolate could be clearly distinguished from B. picturae DSM 16132(T) on the basis of some cultural, physiological and biochemical characteristics. A battery of phenotypic and genetic data obtained in this study suggest that strain HFW-26(T) represents a novel species of the genus Brevibacterium, for which the name Brevibacterium marinum sp. nov. is proposed. The type strain is HFW-26(T) (=JBRI 2001(T)=KCTC 19221(T)=DSM 18964(T)).