Developmental hypomineralized lesions of enamel (DHL) may represent a significant caries-risk factor. The aim of this study was to determine the association between carious lesion severity and DHL in 6- to 12-year-old schoolchildren from Melbourne, Australia.The sample was derived from randomly selected schools in inner Melbourne. A full dental examination was performed at the school. Socio-demographic data, caries experience (DMFT/dmft/ICDAS II) and the consequences of untreated carious lesions (PUFA/pufa) were measured. DHL, molar incisor hypomineralization (MIH) and hypomineralized second primary molar (HSPM) presence were assessed using the European Academy of Paediatric Dentistry (EAPD) criteria.Of the children examined (n = 327), 26.9% had DHL. The prevalence of MIH and HSPM was 14.7% and 8%, respectively. Almost 20% of children had severe carious lesions (ICDAS 5 & 6) in at least one permanent or primary tooth. Ordinal regression analyses indicated that DHL (OR = 2.17; 95% CI: 1.35-3.49) and being born overseas (OR = 2.59, 95% CI: 1.66-4.06) increased the likelihood of severe carious lesions.One of four children had DHL. DHL-affected children had an increased likelihood of presenting untreated severe carious lesions compared with DHL-free children.