AIM: Presence of deep ulcerations (DU) at diagnosis seems to be predictive of a more severe phenotype in adult Crohn's disease (CD). The aim of our study was to investigate if the presence of DU at diagnosis was associated with a more severe disease course over time in children. METHODS: In this monocentric retrospective study, we analysed data from paediatric patients with a new diagnosis of CD from 2009 to 2017. Clinical, laboratory data, treatments and complications were recorded for each patient at diagnosis and at 1, 3 and 5 years of follow-up. Patients were compared according to the presence or absence of DU on colonoscopy. RESULTS: Among the 116 patients included in the study, 52 patients had DU at diagnosis. Comparison showed an increased risk for patients with DU to develop abdominal abscesses (p = 0.045) and to experience more relapses (p = 0.013) at 1 year. At 3 and 5 years, there was no longer any difference between groups. The time from diagnosis to first anti-TNF alpha was shorter in DU patients. CONCLUSION: The presence of DU at diagnosis is associated with more complications during the first year of follow-up but not after, due to a more active therapeutic management.