The present study investigates the consequences of overall justice perceptions on employees' mental health and work-family conflict. While many studies have found that perceiving injustice at work is harmful, little is known about the underlying processes. Based on the allostatic load model, it is hypothesized that mental preoccupation with work, defined as a cognitive state, is a mediator linking overall justice perceptions to employee health. Moreover, we argue that locus of control is a moderator for the mediated relationship. We tested our hypotheses with panel data consisting of 412 Swedish office workers. Results support that mental preoccupation with work mediates the relationship between overall justice and mental health, and overall justice and work-family conflict. Results also reveal that mental preoccupation with work plays a greater mediating role for individuals with an external locus of control. Implications and suggestions for future studies on the emerging relationship between organizational justice and health are discussed.