This paper uses truncated count model with endogeneity and simulated maximum likelihood estimation technique to estimate gender differences in moral hazard in health care insurance. We use the dataset which consists of invoices for all outpatient services from a regional hospital in Croatia. Our theoretical model predicts that higher risk aversion is associated with smaller moral hazard effect. If women are more risk-averse than men, then the moral hazard effect due to health insurance should be lower in women than in men. Whereas the overall results show a statistically significant evidence of moral hazard for the general population, we found economically small but statistically significant larger moral hazard in women than in men.