Much theoretical work has been done on the tonal structure of languages in the Bantu family. However, most of these studies are not supported by physical measurements, or even a consistent model for mapping from linguistic constructs to such measurements. As a first step towards addressing this deficiency, we report on initial measurements regarding the relationship between fundamental frequency and linguistic tone in isiZulu. After choosing a suitable algorithm for pitch extraction, we have correlated a number of linguistically assigned tone values with measured values for fundamental frequency. These measurements indicate a fairly complex relationship between tone and pitch, and suggest that the commonly observed ‘falling' tone in isiZulu may be a context-specific realization of the high tone.