Lezetxiki is a cave in the Gipuzkoan municipality of Mondragón, Basque Country, Spain, which contains an archaeological, paleontological, and paleoanthropological site. It was excavated for the first time between 1956 and 1968 by the priest José Miguel de Barandiarán, and from 1996 to the present under the direction of the professor of the University of the Basque Country Álvaro Arrizabalaga.

It is located in the neighborhood of Garagarza de Mondragón, on the eastern flank of Mount Bostate, one of the hills that make up the Udalaitz massif.

The site has great weight within the Cantabrian context. Lezetxiki culturally belongs to two different phases, the oldest being that belonging to the Acheulean and the most recent to an incipient Mousterian. A woman's humerus was recovered. Its affiliation to either Homo Heidelbergensis or Homo neanderthalensis is being disputed. Two dental remains have been collected from the latter.