Underreporting of occupational injuries was examined in four health care facilities using quantitative, qualitative, and observational data. Occupational Safety and Health Administration logs accounted for only one-third of the workers' compensation records; 45 percent of injured workers followed by survey had workers' compensation claims. Workers reported 63 percent of serious occupational injuries. Underreporting is explained by time pressure and workers' doubts about eligibility, reputation, income loss, and career prospects. Though aware of underreporting, managers subtly believe in workers' moral hazard behaviors.