Industrial relations research has traditionally viewed trade unions as the primary mechanism for employee voice. With the decline in unionism in many advanced industrial economies over the past two decades, new direct non‐union voice mechanisms have been introduced by employers. This focus on the mechanisms for employee voice, however, fails to take account of employees' perceptions of voice. We suggested that employee perceptions of voice vary between the different levels of an organisation and proposed that trade union membership will be more likely to enhance individual employee perceptions of voice at the wider organisational level. Contrary to our expectations, our analysis of 2,949 employees of a public sector scientific research organisation found that union membership had a significant negative impact on employee voice at the organisational level. The article concluded by offering possible explanations for this unexpected finding and the implications for theory, management and future research.