The last two decades have seen a steep increase in the number of studies examining the relationship between workplace bullying and mental health. This comes as no surprise, considering that workplace bullying represents a powerful stressor and a severely traumatic experience that may profoundly shatter people’s assumptions about themselves and the surrounding world. The goal of this chapter is to make an overview of the extant international literature on the relationship between workplace bullying and mental health. After presenting the available meta-analytic findings, the chapter will summarize the most methodologically robust international research investigating the impact of workplace bullying on a diverse array of mental health problems, including depression, anxiety, psychological distress, post-traumatic stress disorder and burnout. Studies focusing on the mental health effects of witnessing bullying and examining reverse causation (i.e. the impact of mental health on the exposure to workplace bullying) will be also reviewed. The chapter will then move on to the available research on individual and work-related moderators of the relationship between workplace bullying and mental health. In the concluding section, the main gaps in current knowledge will be summarized, followed by a discussion of the future research directions needed to enhance our understanding of the link between workplace bullying and mental health.