Mount Chaitén is a volcanic caldera located in the northern Patagonia (Chile), near the Gulf of Corcovado, about 10 km northeast of the town of Chaitén, to the west of the larger Michimahuida volcano. It is widely believed that the last known explosive eruption of Chaitén was related to the formation of a 3–4 km diameter caldera at about 9400 14C years BP. On the basis of the collapse caldera’s volume, this event was estimated to have erupted about 4 km3 of material. With the rejuvenation of Chaitén in 2008, new work has shown that Chaitén may have been the source of a major Holocene rhyolite pumice unit (Mic2) previously ascribed to Michimahuida, with an age <3,820 yrs BP. Prior to the 2008 activity, the caldera was partially filled by an obsidian dome, which may have been emplaced >5,600 years ago, on the basis of obsidian of the same composition having been found in nearby archaeological contexts. In summary, there is growing evidence for previously unknown Holocene eruptions of Chaitén volcano, one of them possibly in the 17th century.