OBJECTIVE This study's purpose was to evaluate the impact of untreated dental caries on the oral health-related quality of life (OHRQoL) of children of low socioeconomic status. METHODS One hundred twelve impoverished 8- to 10-year-olds from a city in southeastern Brazil were selected. OHRQoL was measured using the Child Perceptions Questionnaire (CPQ8-10; total and subscale scores) and its global question on oral health. The clinical examination recorded the prevalence of untreated dental caries (corresponding to a non-zero D or d component in the DMFT or dmft indices). The children were categorized as without untreated dental caries=0 or with untreated dental caries ≥1. Malocclusions and dental trauma were determined using the Dental Aesthetic Index and Andreasen and Andreasen (1994) classification, respectively. Descriptive analysis, Mann-Whitney, chi-square test, and hierarchically adjusted Poisson regression models were employed. RESULTS Eighty-four children (75%) had 1 or more carious teeth. The relative risk of having a negative perception of oral health was greater among the children with untreated dental caries (RR-1:41; 95% confidence interval=1.13-1.75), regardless of gender or malocclusion. CONCLUSIONS Eight- to 10-year-olds with untreated dental caries have a greater relative risk of having a negative perception of oral health status than those without dental caries.