Samoan is a Polynesian language with an ergative case marking system. While ergative and oblique case are marked segmentally, the absolutive case has been thought to be unmarked. I will present fieldwork data in Samoan supporting the hypothesis that absolutive case is marked by a lexical high tone, although this is not necessarily a one-to-one mapping, since high tones also mark other grammatical structures, as well as prosodic boundaries. I will discuss implications of this finding for prosodic typology and for the syntax-phonology interface.