Aim: To describe the occurrence and causes of acquired brain injury (ABI), including traumatic brain injury (TBI) and non-traumatic brain injury (NTBI), among Dutch youth and estimate incidence rates from the data. Patients: Aged 1 month-24 years, hospital diagnosed with ABI in 2008 or 2009. Methods: In three major hospitals in the southwest region of the Netherlands patients with ABI were retrospectively identified by means of diagnosis codes and specific search terms. Results: One thousand eight hundred and ninety-two patients were included: 1476 with TBI and 416 with NTBI. Causes of TBI and NTBI varied among the age groups 0-4, 5-14 and 15-24 years, with accidents (in traffic or at home) being the most common cause of TBI and hypoxic-ischemic events for NTBI, in all groups. The estimated yearly incidence rates per 100 000 for mild-moderate-severe TBI were 271.2-15.4-2.3 (0-14 years) and 261.6-27.0-7.9 (15-24 years), for mild-moderate-severe NTBI they were 95 Conclusion: More than 15% of TBI and NTBI in children and youth is classified as moderate or severe, with causes of TBI and NTBI varying among age groups. Based on the occurrence of ABI in three hospitals, the estimated incidence of ABI in children and youth in the southwest region of the Netherlands is substantial.