We aimed to identify sociodemographic predictors of compliance after receiving a personalised reminder on lacking vaccinations against MMR (Measles, Mumps, Rubella) and/or HPV (Human Papilloma Virus) among parents of Danish adolescent girls. A nationwide register-based study, including all 14-year-old girls (15 May 2014–14 May 2015) lacking either MMR, HPV-vaccination or both. Vaccination-compliance following a postal reminder was modelled using multivariable logistic regression and included the following socio-demographic predictors: maternal age, education, employment and ethnicity. Birth order, number of siblings, family-structure, location of residence, and household income. The parents of 9692 girls received a reminder. Out of 4940 exclusively lacking an HPV-vaccine, 15.3% were subsequently vaccinated. Among 2026 only lacking an MMR vaccination, 8.5% were vaccinated. Among 2726 girls lacking both, 5% received an HPV, 4.4% an MMR and 5.4% received both vaccinations. We identified sociodemographic differences between reminderletter-compliers and non-compliers, also according to vaccination types. Non-western descendants were more likely to receive HPV-vaccination, although the association was only significant for those who only lacked HPV (OR 2.02, 95% 1.57–2.59). For girls only lacking an MMR, regional differences were identified. Among girls lacking both vaccines, girls of mothers with intermediate (OR 0.63, 0.42–0.95) or basic education (OR 0.43, 0.24–0.75) were less likely to be vaccinated compared to girls of higher educated mothers. Reminders were in particular effective in increasing HPV uptake among immigrants of non-Western ethnicity. We found reminders to be less effective among less educated mothers whose daughters lacked both vaccines. To increase the coverage in this group, additional interventions are needed.