A Gram-reaction-negative, non-motile, aerobic bacterium, designated HJ50(T), was isolated from deep seawater of the East Sea, South Korea. Cells were ovoid to rod-shaped (0.5-0.8x1.3-3.0 mum), often with unequal ends, suggesting a budding mode of reproduction. The strain had an absolute requirement for sea salts and tolerated up to 20 % (w/v) sea salts. Propionate, dl-lactate, 2-ketogluconate, 3-hydroxybutyrate and rhamnose were used as growth substrates, but not mannitol, salicin, 4-hydroxybenzoate or acetate. The major fatty acid was summed feature 7 (C(18 : 1)omega7c/omega9t/omega12t) and the DNA G+C content was 59.0+/-0.1 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that this strain was affiliated with the genus Roseovarius. Similarities between the 16S rRNA gene sequence of strain HJ50(T) (1430 nt) and those of type strains of members of the genus Roseovarius were 94.1-96.3 %. DNA-DNA relatedness values between strain HJ50(T) and the type strains of members of the genus Roseovarius were low (1.3-24.6 %). Physiological and biochemical differences support assignment of strain HJ50(T) to the genus Roseovarius as a representative of a novel species. The name Roseovarius halotolerans sp. nov. is proposed, with HJ50(T) (=KCTC 22224(T) =LMG 24468(T)) as the type strain.