A yunnanolepiform antiarch (placoderm fish) is recorded from the Givetian Dong Tho Formation of Quang Binh Province, central Vietnam. This and other fishes from the same locality occur in marginal marine, detrital facies, with plant remains and lingulid brachiopods that indicate a nearshore to deltaic environment. Yunnanolepiform antiarchs were hitherto known exclusively from the Lower Devonian of the South China block. The new occurrence of this group well south of the Song Ma suture suggests close links between the Indochina and South China blocks in Middle Devonian time. The massive sandstone exposures of the Dong Tho Formation may be a southern extension of the Do Son Sandstone Formation of the Hai Phong area, which is located on the South China block.