Eucryptotermes Holmgren, 1911, comprises 2 species of Neotropical drywood termites with phragmotic head soldiers. We report the presence of Eucryptotermes hagenii (Müller, 1873) in native forests of the Chaco Dominion and Chaco Province, enlarging its distribution and recording the genus and species for the first time in Argentina. Eucryptotermes hagenii abundance was estimated as intermediate by standardized sampling. Eighteen morphometric characters were measured in soldiers and alates, and 9 of them provided new data. The colonies, located inside living trees trunks and dead wood, were composed of reproductives, soldiers, pseudergates, and immatures.