Abstract Background Unpaid labour has recently been recognised as an important yet neglected social determinant of health. Our aim was to investigate the gendered trends in unpaid labour/domestic work by educational level in prime working-age Swedish adults (30-49 years) from 2004-2022. Methods The study is based on a postal survey sent to a random general population sample of adults from central Sweden in 2004, 2008, 2012, 2017 and 2022. The 30-49-year age group included between 5,500 and 12,200 respondents depending on the survey year. Trends in hours spent in domestic work and in experiencing domestic work as burdensome by gender and educational level were estimated by age-standardised proportions with corresponding 95% confidence intervals. Results Women reported spending more time in domestic work than men throughout every survey period from 2004 to 2022. For example, in 2022, 31% of women spent more than 20 hours per week in domestic work compared to 20% of men. Over time, hours spent in domestic work decreased in women whereas no trend was observed in men. Among women, educational level appeared to make no difference to prevalence of high domestic work time whereas, among men, it was consistently greater among those with higher educational levels. In general, women experienced domestic work as burdensome to a higher degree than men did. Conclusions As gender differences in unpaid labour/domestic work persist in Sweden, more effort is needed to implement social policies to increase men’s participation in domestic work, especially among men with low and middle educational levels, which has the potential to reduce gendered health inequities. Key messages • Amongst Swedish adults aged 30-49 years, the gender gap in unpaid labour has declined during the last two decades, but this is only due to women reducing their domestic work time. • For men, prevalence of high domestic work time was consistently greater among those with higher educational levels, whereas no difference was observed among women.