Union representatives were surveyed throughout Belgium between August and December 2021 through an online questionnaire ( N = 469) to assess the relationship between trade union representatives’ perception of social dialogue quality and change in workers’ physical and mental health during the COVID-19 pandemic. We use a modified Poisson regression for binary outcomes controlling for company characteristics, pre-pandemic self-reported health and pandemic-related measures. A total of 30.1% of the sample reported the social dialogue quality has deteriorated during the pandemic. Relative risks (RRs) of poor physical and mental health when social dialogue has worsened are 1.49 (95%CI (95% confidence interval) = 1.03; 2.15) and 1.38 (95%CI = 1.09; 1.74). Controlling for pandemic-related measures slightly reduces the risk of both poor mental (RR = 1.25; 95%CI = 0.84; 1.87) and physical health (RR = 1.18; 95%CI = 0.94; 1.49). Although based on self-reported variables, the study shows an association between poor social dialogue quality and health and underlines the need to look at company-level collective negotiation. ; info:eu-repo/semantics/published