While processes of loanword adaptation in Sakha (Yakut) have been well-studied, contemporary speakers tend to use the original Russian pronunciations, and little attention has been paid to the interaction of these unadapted loanwords with native morphology. This study investigates vowel harmony processes in spoken Sakha, with a focus on suffixation patterns in borrowed words. The data was obtained from interviews conducted with six native speakers of Sakha who completed an elicitation task and a Likert-scale task in which they were asked to produce and rate plural and possessive forms of native and borrowed words. In native and fully adapted loanwords, speakers consistently produced and rated most highly the expected suffix variants based on the stem-final vowel. For unadapted loanwords, there were also consistent patterns, but the preferred suffix was less likely to harmonize with the stem-final vowel. Several factors influenced the choice of suffix, including whether the word was harmonic; the height of the suffix vowel; and the written form. For non-native words, vowel harmony violations were more likely to involve front or round triggers, and the preferred suffixes were the back unrounded variants