This study was designed to assess the reasons for health insurance coverage in a population covered by the Family Health Strategy in Brazil. We describe overall health insurance coverage and according to types, and analyze its association with health-related and socio-demographic characteristics. Among the 31.3% of persons (95% CI: 23.8-39.9) who reported "health insurance" coverage, 57.0% (95% CI: 45.2-68.0) were covered only by discount cards, which do not offer any kind of coverage for medical care, but only discounts in pharmacies, clinics, and hospitals. Both for health insurance and discount cards, the most frequently cited reasons for such coverage were "to be on the safe side" and "to receive better care". Both types of coverage were associated statistically with age (+ 65 vs. 15-24 years: adjusted odds ratios, aOR = 2.98, 95% CI: 1.28-6.90; and aOR = 3.67; 95% CI: 2.226.07, respectively) and socioeconomic status (additional standard deviation: aOR = 2.25, 95% CI: 1.62-3.14; and aOR = 1.96, 95% CI: 1.34-2.97). In addition, health insurance coverage was associated with schooling (aOR = 7.59, 95% CI: 4.44-13.00) for complete University Education and aOR = 3.74 (95% CI: 1.61-8.68) for complete Secondary Education, compared to less than complete Primary Education. Meanwhile, neither health insurance nor discount card was associated with health status or number of diagnosed diseases. In conclusion, studies that aim to assess private health insurance should be planned to distinguish between discount cards and formal health insurance.