ObjectivesTo describe distributions and concordance of retinal microvasculature measurements in a population-based sample of Australian parent–child dyads at child age 11–12 years.DesignCross-sectional Child Health CheckPoint study, between waves 6 and 7 of the national population-based Longitudinal Study of Australian Children (LSAC).SettingAssessment centres in seven Australian cities, February 2015–March 2016.ParticipantsOf the 1874 participating families, 1288 children (51% girls) and 1264 parents (87% mothers, mean age 43.7) were analysed. Diabetic participants and non-biological pairs were excluded from concordance analyses.Outcome measuresRetinal photographs were taken by non-mydriatic fundus camera. Trained graders scored vascular calibre using semi-automated software, yielding estimates of central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) and arteriolar–venular ratio (AVR). Pearson’s correlation coefficients and multivariable linear regression models assessed parent–child concordance. Survey weights and methods accounted for LSAC’s complex sampling, stratification and clustering within postcodes.ResultsMean (SD) of CRAE and CRVE were larger in children (159.5 (11.8) and 231.1 (16.5) μm, respectively) than parents (151.5 (14.0) and 220.6 (19.0) μm), yielding similar AVR (children 0.69 (0.05), parents 0.69 (0.06)). Correlation coefficients for parent–child pairs were 0.22 (95% CI 0.16 to 0.27) for CRAE, 0.23 (95% CI 0.17 to 0.28) for CRVE and 0.18 (95% CI 0.13 to 0.24) for AVR. Mother–child and father–child values were similar (0.20 and 0.32 for CRAE, 0.22 and 0.29 for CRVE, respectively). Relationships attenuated slightly on adjustment for age, sex, blood pressure, diabetes and body mass index. Percentiles and concordance are presented for the whole sample and by sex.ConclusionsArteriolar and venular calibre were similar to previously documented measures in midlife adult and late childhood populations. Population parent–child concordance values align with moderate polygenic heritability reported in smaller studies.