The Brazilian private health insurance sector has operated since 1940’s without regulation. In 1998, the Brazilian Government stating the regulation of this sector. The reform improved the health insurance coverage level, stating no limit to physician visits. The aim of this paper is to measure the effects – in particular on the utilization physician visits - of reform on private health insurance market. Three econometric methods were used: Poisson Regression, Negative Binomial Regression and Count Data Quantile Regression. Data come from the National Household Survey Sample (Pesquisa Nacional de Amostra de Domicilios-PNAD) for 1998 (before regulation) and 2003 (after regulation). The estimator of difference-in-difference is used to estimate the impact of regulation. The results showed that individuals with health insurance have greater number of physician visits, suggesting presence of moral hazard.