The aim of this study was to describe the patterns of multimorbidities of oral clinical conditions in children. The association between social position and number of oral clinical conditions, and the relationship of social position and number of oral clinical conditions with oral health-related quality of life [OHRQoL, measured using the Brazilian Child-Oral Impacts on Daily Performance (Child-OIDP)] were also investigated. The study analysed data on 7,208 children, 12 yr of age, from the Brazilian Oral Health Survey (SBBrasil Project). Cluster analysis based on the observed/expected (O/E) ratios identified six significant clusters of oral clinical conditions: (i) dental caries and missing teeth; (ii) dental caries and dental trauma; (iii) dental trauma and gingivitis; (iv) dental caries, missing teeth, and dental trauma; (v) dental caries, dental trauma, and gingivitis; and (vi) all oral clinical conditions. Ordinal regression showed that poor social position was associated with a large number of oral clinical conditions. Poisson regression demonstrated that low social position and greater number of oral clinical conditions increased the likelihood of poor OHRQoL (Child-OIDP extent). The four oral clinical conditions clustered into six distinct clusters among Brazilian children. Multimorbidity of oral clinical conditions predicted poor OHRQoL. Social position was of high relevance to multimorbidity of oral clinical conditions and children′s OHRQoL.