This article reports results of a research on the interdental segments [t ], [n ], [1 ] in correlation with the alveolar phonemes /t/, /n/, /1/ of the phonological system of the Mapuche language spoken in Tolten and San Jose de la Mariquina, coastal areas of La Araucania and Los Rios, Chile.lhe corpus has been constituted on the basis of 19 surveys of one hundred and sixteen lexical items each, which have been transcribed according to the International Phonetic Alphabet (IFA). lhe phonological analysis of the segments has been carried out on the basis of the distributional method, complemented with the observation of the phonic perception of the speakers themselves from the areas under study. lhe results allow us to conclude that, in the southern zone of the coastal sector, said segments are in force; although their consistency in terms of phonological function in relation to its alveolar counterparts are affected.