PURPOSE: The social restrictions resulting from the COVID-19 pandemic had a great impact on the routine of children and adolescents, with important consequences such as sleep, eating, and psychological/psychiatric disorders. Even though there are no studies on the subject, it is possible that these changes in habit and routine have also affected arterial stiffness (AS) in this population, which is an important predictor of cardiovascular risk. This study aimed to assess possible changes in AS, anthropometry, and quality of life (QoL) resulting from the COVID-19 pandemic in children and adolescents. METHODS: A controlled observational cross-sectional study was performed with 193 children and adolescents aged 9 to 19 years, allocated into two groups: before the pandemic (BPG) and one year after the pandemic (APG), matched by age and sex. Cardiovascular parameters were measured non-invasively by brachial artery oscillometry with a portable device. The main AS indices evaluated were the augmentation index (AIx) and pulse wave velocity (PWV) derived from the aortic pulse wave. QoL was assessed using the Paediatric Quality of Life Inventory version 4.0 (PedsQL 4.0). RESULTS: Regarding QoL, the APG showed a worsening in emotional (p=0.002) and school-related (p=0.010) aspects. There was no statistically significant difference for most anthropometric parameters, except for the hip circumference, which was higher in the APG group (p<0.001). The main predictor of AS in the paediatric population, AIx@75, was shown to be increased in the APG group (p<0.001). Other cardiovascular parameters were also different, such as peripheral (p=0.002) and central (p=0.003) diastolic blood pressure, stroke volume (p=0.010), and total vascular resistance (p=0.002), which were shown to be decreased in the APG group, while the heart rate was increased (p<0.001). CONCLUSIONS: Our results show that routine changes resulting from the period of social isolation increased cardiovascular risk in children and adolescents, evident by the increase in AIx@75, which is considered to be an important marker of cardiovascular risk in the paediatric population.