BACKGROUND: Most of the existing studies demonstrating the relationships between health literacy and health service use have been conducted outside Europe and cannot be generalised to European healthcare systems. Moreover, the majority of studies measure healthcare use via self-reports. This study investigated whether health literacy is related to the use of health services measured objectively via patient records in a European country. METHODS: 9617 members of a Belgian health insurance fund (59% females, ages 18-88 years, mean age 55.8 years) completed an online questionnaire including the 16-item European Health Literacy Survey Questionnaire (HLS-EU-Q) and agreed to have their responses linked to the insurance fund's health service use records. A two-part model approach was used to assess the association between health literacy and the use of healthcare services and the costs related, adjusting for personal and behavioural characteristics. RESULTS: Low health literacy is associated with more admissions to 1-day clinics, general practitioner (GP) home consultations, psychiatrist consultations and ambulance transports, and with longer stays in general hospitals. Associations with psychiatric hospitalisations and specialist consultations are also found but are not significant when correction for multiple comparisons is applied. In contrast, health literacy is not significantly related to the number of GP consultations, admissions to 1-day surgical clinics or emergency consultations. The relationship between health literacy and medication use is inconsistent. CONCLUSION: The results partly confirm that low health literacy is associated with greater use of healthcare services, and especially of more specialised services. Improving the health literacy of the population can be an effective strategy to promote a more (cost)-effective use of the healthcare services and thus contribute to population health.