Purpose: This paper aims to discuss how trade union leaders deal with the implementation of Industry 4.0 (I4.0). The study is circumscribed to the Brazilian automotive sector and came from a human-centric (Industry 5.0) concern related to issues such as organisational learning, knowledge, innovation and workplace learning. Design/methodology/approach: Case studies in two truck plants related to union participation during new product and process implementation based on Industry 4.0. Semi-structured interviews with union leaders from both plants were conducted to determine the subtle similarities and differences between the two polar types. Findings: The findings pointed out that human resources and workplace learning must be reviewed to prepare workers to face I4.0. Four themes are explored: modernisation origins; negotiation process; workers' concerns; and results and lessons learned. The findings highlight concerns about employees and job loss; replacement of workers by technological devices; workplace learning and the trade union perspective; and influence of the country's economic situation on I4.0 implementation in social systems dependent on worker tacit knowledge. Originality/value: This paper presents labour union leaders' perspectives related to the impact of I4.0 and contributes to a better understanding of industry-worker workplace learning.