Early childhood caries (ECC), dental caries affecting the primary teeth in preschool aged children, is prevalent, especially among low social economic groups in developing countries. Treatment of ECC in developing country is almost nonexistent, so that it can cause more serious complications. Untreated ECC can affect on quality of life in preschool aged children. This cross-sectional study aim was to evaluate association between untreated ECC and quality of life of preschool children (aged 3-5 years). This cross sectional study was conducted on September-October 2018 in playgroups/kindergartens in Ilir Barat I Subdistrict, Palembang and consisted of 334 preschool children-parent pairs. Untreated ECC was assessed by PUFA/pufa index and preschool children's quality of life by ECOHIS instrument. Association between untreated ECC and quality of life were analyzed using the Fisher's exact test with 95% CI. The result showed that ECC prevalence was 84.1% and the pufa was developed in 39.1% untreated ECC. There wasa significant association between untreated ECC and preschool children's quality of life (p<0,05). Children with ECC in this study had a good quality of life (95.2%), sufficient (4.2%), and bad (0.6%). Similarly, parents who had children with ECC had good quality of life (86.6%), sufficient (10.8%), and bad (2.4%). ECC that was not treated was statistically related to the quality of life of children and their parents (p <0.05). The conclusion of this study is that ECC that is not treated can affect the quality of life of children and their parents so that the ECC must be dealt with immediately.