As is typical of African languages, there is little published material on Kimatuumbi, a Bantu language spoken in Tanzania. The grammatical sketch and lexicon published by Krumm in 1912 give no indication of vowel length and tone which are two of the most interesting and complex phonological properties of the language. The descriptive account of these properties and of rule interaction in Kimatuumbi phonology bears on a nember of important theoretical issues, including theories of interaction between phonology and syntax, lexical phonology, the geometric representation of vowel features, and the theory of prosodic representations. This study both broadens our understanding of the structure of African languages and provides data which are crucial for resolving certain questions in contemporary phonological theory.