Lawu is a severely endangered, undocumented Ngwi (Loloish) language spoken in Yunnan, China. This paper presents a preliminary sketch of Lawu phonology based on lexico-phonetic data recorded from two speakers in 2008, with special attention to the tone splits and mergers that distinguish Lawu from other Ngwi languages. All tone categories except Proto-Ngwi Tone *3, a mid level pitch, have split, conditioned by the voicing of the initial segment. In the conditioning and effect of these tone splits, Lawu shows affinity with other Central Ngwi languages such as Lisu and Lahu and is provisionally classified as a Central Ngwi language.