Objectives To identify socioeconomic and regional inequalities of pap smear coverage in the state of Rio Grande do Sul. Methods An ecological study based on data of the 2011-2012 national health information system to estimate the annual coverage of pap smears for the overall female population of the state and for women without private health insurance. We estimated annual pap smear coverage according to the Municipal Social Vulnerability Index and health macro-regions and regions of the state. Results The percentage of women without private health insurance ranged from 38.1% to 94.2% in the health regions. Pap smear coverage was 17.3% for the overall female population and 23.8% for women without private health insurance. Pap smear coverage was higher in more socially vulnerable municipalities and regions with a higher percentage of women with private health insurance. Conclusions The prevalence of private health insurance should be considered in studies that address the coverage of the Brazilian Unified Health System (SUS).