Background: Children with mild or asymptomatic COVID-19 represent the majority of paediatric cases. Hospitalisation and critical care are required only in a small proportion of SARS-CoV-2 positive children who present severe symptoms, like interstitial lung disease. A quarter of children experience persistent symptoms some months later after being hospitalised, and they need to be properly followed up. Case presentation: The authors describe a case report of long-COVID in a 5 years old child, who was previously hospitalized for a severe case of COVID-19 (an interstitial lung disease requiring oxygen), followed up in 3 months in our Pediatric Department. Results: After 3 months post-hospitalisation, despite his clinic history, the clinical examination was normal, during the six-minute walking test he did not desaturate, the spirometry was in the norm and the lung ultrasound did not show any pathological findings. Conclusion: We reported a case of a child previously hospitalised for interstitial lung disease with long-COVID, who has been followed up 3 months after the hospitalisation by our Department of Pediatrics of the University ‘Luigi Vanvitelli’. Based on our experience, even in children who have experienced a severe form of COVID-19 disease and who continue to exhibit symptoms, a proper follow-up can demonstrate a full recovery in a few months.