A novel halophilic archaeon (strain B1(T)) belonging to the genus Natronococcus was isolated from shrimp jeotgal, a traditional fermented food from Korea. Colonies of this strain were orange-red and cells were non-motile cocci that stained Gram-variable. Strain B1(T) grew in 7.5-30.0 % (w/v) NaCl and at 21-50 degrees C and pH 7.0-9.5, with optimal growth occurring in 23-25 % (w/v) NaCl and at 37-45 degrees C and pH 7.5. Strain B1(T) was most closely related to the type strain of Natronococcus occultus, with which it shared 97.91 % 16S rRNA gene sequence similarity. Within the phylogenetic tree, this novel strain shared a branching point with N. occultus and occupied a phylogenetic position that was distinct from the main Natronococcus branch. The degree of DNA-DNA hybridization with the type strain of N. occultus, the most closely related species phylogenetically, was 16.4 %. On the basis of these results, it is concluded that strain B1(T) represents a novel species of the genus Natronococcus, for which the name Natronococcus jeotgali is proposed. The type strain is B1(T) (=KCTC 4018(T)=DSM 18795(T)=JCM 14583(T)=CECT 7216(T)).