Little is known about the effects of informal care-giving on employees' absenteeism due to illness. This paper therefore provides a longitudinal analysis of the consequences of taking on informal care-giving for men's and women's working hours and workplace absenteeism due to illness. Data were taken from the Dutch Labour Supply Panel (waves 2004–2018); 495 of the 6,452 male observations in this panel and 696 of the 5,961 female observations had taken on informal care-giving. It was tested whether respondents who became (intensive) informal carers were more likely than respondents who remained non-care-givers to reduce their work hours or stop working between waves t and t1, or to be absent from work due to illness in wave t1. (Multinomial) logistic regression analyses showed that taking on informal care reduced women's working hours when the care they provided was intensive, but not men's. The predicted probability of women reducing their work hours was 12 per cent if they had remained non-care-givers between waves t and t1, 15 per cent if they had started giving non-intensive care and 19 per cent if they had begun providing intensive help. In addition, starting to provide (non-intensive) informal care increased the risk of workplace absenteeism among both women and men. The study highlights the need for workplace policies that prevent female carers from reducing their work hours, and enable male and female carers to continue working in a healthy way.