The growing literature on high performance workplace systems suggests that in a unionised environment such systems can be advantageous for workers. This paper reports on a study of New Zealand dairy workers’ views on the introduction of a hpws. It reports little evidence to support the more optimistic claims in the literature. But it also reports that union members still support hpws, primarily for reasons of job security. Thus notwithstanding many of the findings, the paper concludes that there are limited grounds for a degree of optimism about the potential of union involvement in hpws to enhance worker voice.