This paper draws from a large corpus of natural data to provide a descriptive account of vowel harmony in Nkami, an endangered undocumented Guang (Kwa) language of Ghana. Like most Kwa languages, Nkami has nine phonemic vowels with robust ATR harmony. Besides ATR harmony, it also shows evidence of rounding and height harmonies though the latter are restricted and epiphenomenal to ATR harmony. Typical of most nine-vowel ATR languages, Nkami displays evidence of [+ATR] dominance and the direction of the [+ATR] assimilation is predominantly regressive. Aside from morpheme internal ATR harmony, ATR harmony occurs in stems and prefixes, loanwords, pronominal possessions, compounds and across word boundaries. Though the low vowel /a/ is neutral, with no noticeable [+ATR] phonetic variant and is predictably opaque to [+ATR] spread, there is an instance where it appears to alternate with the mid vowel /e/. Both height and rounding harmonies occur in the contexts of pronouns and verbal prefixes. However, while the direction of assimilation of the former is regressive, that of the latter is progressive. Thus, Nkami differs from other Guang languages in the sense that whereas other Guang languages exhibit evidence of regressive root-controlled rounding harmony, Nkami shows evidence of progressive rounding assimilation that is prefix-controlled.