Immigrants experience many obstacles in obtaining jobs with comparable pay and conditions to native workers. Arguably, unionisation could offer migrant workers the mechanism to obtain better pay and conditions. This paper examines whether migrant workers have benefited from unionisation in terms of pay, pensions and health insurance in Ireland. Based on a large-scale national survey, we find that union membership delivers a modest wage premium of a relatively similar magnitude to both nationals and immigrant workers. Unionised immigrants are twice as likely as non-unionised immigrants to earn above the median hourly earnings and have greater pension coverage. In particular, immigrants from the new accession states in the European Union, with the lowest mean hourly earnings of any immigrant group, gain the most from union membership. Nonetheless, Irish nationals enjoy greater benefits from membership than immigrant workers. Addressing this discrepancy will require a greater focus by unions on organising immigrant workers.