Negative priming refers to an inhibitory effect, in which responding is slower when an attended target is identical, or related to a previously ignored distractor. It has been suggested that the processes underlying this effect are important for maintaining attentional focus and orientation. A version of this paradigm, in which subjects attended to digits presented to the RVF, and ignored digits presented to the LVF was employed with two split-brain subjects and seven normal controls. The task was to categorize RVF digits as odd or even. Each of the split-brain patients showed significant amounts of negative priming from ignored LVF distractors, as did the normal control subjects. It is concluded that even in the split-brain there are rich attentional interactions with respect to complex attributes encoded within each hemisphere. It is suggested that these rely on interaction between cortical and subcortical processing, and may play an important role in relation to the unified and apparently well integrated behaviour of commissurotomy patients in everyday settings.