Purpose The aims of this study are: (1) to describe the prevalence of needed and implemented work adjustments in a representative sample of Dutch employees with a chronic disease; and (2) to assess the effects of needed and implemented work adjustments on sick leave. Methods The prevalence of work adjustments was assessed in employees with a chronic disease, aged between 15 and 65 years (n = 7,687) from the 2007 Netherlands Working Conditions Survey (NWCS). Of these, N = 2,631 employees participated in the Netherlands Working Conditions Cohort Study (NWCCS) measurements in 2008 and 2009. The NWCCS data were used to investigate the effects of work adjustments on sick leave. All data were self-reported. A repeated measures ANOVA was performed to analyse differences in sick leave in 2007, 2008 and 2009 between employees with and without a need for work adjustments, for those who reported an implemented work adjustment and those who did not. Results In 2007, the prevalence of implemented work adjustments among Dutch employees with a chronic disease was 22 %, while 30 % reported the need of a work adjustment. In employees with and without a need for work adjustments in 2007, a work adjustment in 2008 was significantly associated with a decrease in sick leave from 2007 to 2009. Conclusion The need for work adjustments is higher than the implementation of work adjustments. Work adjustments should be considered more often for employees with chronic diseases, because implementation of a work adjustment is associated with a decrease in sick leave.