Purpose: The purpose of this paper is to identify the barriers to implementing the national vaccination guidelines and to propose potential intervention strategies to increase vaccination rates in children with rheumatic diseases. Methods: A cross-sectional descriptive study, conducted in a tertiary hospital in Athens, evaluated the vaccination coverage among 80 pediatric patients with rheumatic diseases, using a 29-item questionnaire. Children up to 16 years of age with delayed or missed vaccine doses were assessed for factors contributing to their incomplete vaccination status. Results: The overall vaccination rate was 75% (N = 80). The most commonly missed vaccines were the second doses of MMR (15%) and VAR (11%). Based on our age-group classification, children under 2 years of age had missed the DTaP–IPV and HBV vaccine at 6.2%. Among children aged 2 to 6 years, the MMR (17.5%) and VAR (11%) vaccines were most frequently missed. By 10 years of age, the MMR-VAR and HAV vaccines had not been administered in 7.3% and 5% of children respectively, while at 10-12 years, the Tdap and MPV4 vaccines were missed at 28% and 22% of cases. For children ? 12 years, HPV (44%) and Tdap vaccines (16%) had been omitted. The COVID-19 vaccinated children were 47% (5 to 12 years old) and 52% (? 12 years old). Of all vaccinated children, 41% reported a COVID-19 infection 6-12 months post-vaccination. Conclusion: The vaccination rates of the Greek pediatric population with rheumatic diseases in our center are adequate, compared to literature reports from other centers.