ObjectiveThis study examined the association between workplace mistreatment and occurrence, duration, and costs of sickness absenteeism. MethodsWe used the 2010 National Health Interview Survey and considered 13,807 employed adult respondents. We used a zero-inflated negative binomial (zinb) model to examine the association between exposure to workplace mistreatment and the occurrence and number of workdays missed due to illness/injury in the preceding 12 months. ResultsIn 2010, 7.6% of US workers employed at the time of the survey reported having been mistreated at their workplace. Both occurrence and duration of sickness absence were higher for mistreated than for non-mistreated workers. The zinb results showed that being mistreated was associated with a 42% increase in the number of missed workdays, controlling for covariates. The marginal effect analysis showed that lost workdays differed by 2.45 days between mistreated and non-mistreated workers. This implies that workplace mistreatment was associated with $4.1 billion, or 5.5%, of sickness absenteeism costs in 2010. ConclusionsWorkplace mistreatment is associated with sickness absence in the United States. While a causal relationship could not be established due to the cross-sectional design of the study, this study reveals the economic importance of developing workplace mistreatment prevention strategies. Am. J. Ind. Med. 57:202-213, 2014. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.