The evolutionary relationships among extinct African hominin species are highly debated and largely unresolved, due in part to a lack of molecular data. Even within taxa, it is not always clear, based on morphology alone, whether ranges of variation are due to sexual dimorphism versus potentially undescribed taxonomic diversity. For Paranthropus robustus, a Pleistocene hominin found only in South Africa, both phylogenetic relationships to other taxa, and the nature of intraspecific variation are still debated. Here we report the first successful mass spectrometric sequencing of enamel proteomes from four ca. 2 million years old dental specimens morphologically identified as P. robustus from the site of Swartkrans.