The presence of sixbar grouper Epinephelus sexfasciatus (Valenciennes, 1828), Perciformes: Serranidae, was reported for the first time in Penghu Archipelago, south-western Taiwan. Two specimens were caught by hook-and-line in 28 June 2012. The species was formerly unrecorded in the Penghu and all Taiwanese waters before this paper and thus extended geographical distribution at least 500 km northward of the previously reported. The probably reasons include: (1) E. sexfasciatus is rare species and ignored due to misidentification as the other groupers, (2) climate change and global warming made the occurrence of poleward shift.