Objective: To describe patient presentation characteristics and outcomes for people aged 16–18 years pre, during and post a planned youth mass gathering event (MGE): ‘Schoolies week’ on the Gold Coast, Queensland, Australia. Methods: This was a retrospective observational study, including patient presentations by all young adults requiring care in the ED or in‐event health services (EHS) over a 21‐day period in 2014. Data analysis included descriptive and inferential statistics. Results: A total of 1029 patient presentations were made by people aged 16–18 years to the ED and EHS over the 21‐day study period (139 pre, 695 during [275 in ED, 420 in EHS], 195 post Schoolies week). Some ED patient characteristics and outcomes varied between the pre, during and post Schoolies periods, such as patients age (P