Karitiana, an endangered language from the Tupi stock, Arikem family, spoken in the state of Rondonia in Brazil, exhibits a number of interesting phenomena concerning stop consonants at the end of words. In particular, voiceless stops are always unreleased word-finally. This phenomenon has been observed as a occasional variant of stops in English (Laver 1994, Ladefoged & Maddieson 1996) and in a number of other languages such as Bamileke (Westermann & Ward 1952) and Efik (Cook 1969), and is systematic in Karitiana. Unreleased final stops are also common in Tupi languages and have been described by several researchers (e.g. Moore 1984; Galucio 1994, 1996; Gabas Jr. 1998, 1999; Picanço 1999; Storto 1999; Rose 2000). Such facts have rarely been described in a detailed manner. This paper describes some phonetic and phonological aspects of the nature of these sounds when they appear word finally. More specifically, three points will be examined: (i) voiceless stop consonants (there are no phonemic voiced consonants in Karitiana); (ii) nasal consonants, which have been described as unreleased word finally by Storto (1999), and (iii) the phonological behavior of these consonants in context.