BACKGROUND: Eyes are frequently injured in occupational accidents. What is the preventive effect of mandatory eye protection in metalworking? METHODS: The injury incidence was determined before and after eye protection became mandatory in a metalworking yard. RESULTS: The incidence declined from 6.09 to 0.42 injuries per million working hours after eye protection became mandatory. CONCLUSIONS: Mandatory eye protection among metalworkers in Norway has high potential for preventing eye injuries and should be implemented.