Objectives To determine the impact of the first lockdown in the Netherlands’ measures during the COVID-19 pandemic on the number and type of trauma-related injuries presenting to the emergency department (ED). Design A single-centre retrospective cohort study. Setting A level 2 trauma centre in Breda, The Netherlands. Participants All patients with trauma seen at the ED between 11 March and 10 May 2020 (the first Dutch lockdown period) were included in this study. Comparable groups were generated for 2019 and 2018. Main outcome measures Primary outcomes were the total number of patients with trauma admitted to the ED and the trauma mechanism. Secondary outcomes were triage categories, time of ED visit, trauma severity (Injury Severity Score (ISS) >12), anatomical region of injury and treatment. Results A total of 4674 patients were included in this study. During the first months of the COVID-19 pandemic, there was a decrease of 32% in traumatic injuries at the ED (n=1182) compared with the previous years 2019 (n=1717) and 2018 (n=1775) (p<0.001). Sports-related injuries decreased most during the lockdown (n=164) compared with 2019 (n=386) and 2018 (n=367) (p<0.001). We observed more frequent injuries due to a fall from standing height (p<0.001) and work-related injuries (p<0.05). The mean age was significantly higher (mean 48 years vs 42 and 43 years). There was no difference in anatomical place of injury or ISS >12. The amount of patients admitted for emergency surgery was significantly higher (14.6% vs 9.4%; 8.6%, p<0.001). Seven patients (0.6%) tested positive for COVID-19. Conclusions Measures taken in the COVID-19 outbreak result in a predictable decrease in the total number of patients with trauma, especially sports-related trauma. Although the trauma burden on the emergency room appears to be lower, more people have been admitted for trauma surgery, possibly due to increased throughput in the operating theatres.