A new species of threadfin bream, Nemipterus andamanensis n. sp. from the Andaman Islands is described and figured. N. andamanensis resembles N. marginatus (Valenciennes, 1830) in general body form and colour pattern, but differs from the latter by having four yellow stripes on the head region, upper lobe of caudal fin and filament yellow, and lower lobe of caudal fin pinkish. The mitochondrial cytochrome oxidase C subunit I (COI) gene sequence comparison with close species revealed that Nemipterus andamanensis n. sp. has distinct genetic divergence (8.5%) from Nemipterus marginatus and other species of the genus occurring in the area.