Abstract Background Acute Respiratory Infections (ARIs) have a relevant impact on public health in terms of prevalence and costs associated with the diseases. The COVID-19 pandemic highlighted the need to adopt accurate surveillance systems to respond to new emergencies and meet the demand for access to care. The aim of our work is to describe the accesses at the Emergency Departement (ED) of the Pisa University Hospital (AOUP), Italy, for ARIs, from 2017 to 2021. Methods A retrospective analysis of electronic medical records from the AOUP was conducted from January 2017 to December 2021. The analysis focused on ED admissions and positive lab test results, examining their correlation with ED visits caused by ARI. Multiple linear regression models were used to understand the influence of viral laboratory results on ARI-related ED admissions, adjusting the results for age. The study also assessed the contribution of each virus incausing ARI within different age groups. Results 33,101 (annual average 5,520) ARI admissions in ED were registered, resulting in 7,426 hospital admissions (22.8%, annual average 1,163) with a seasonal pattern between week 42 of each year and week 17 of the following year. The reduction in emergency room admissions in 2020 (weekly average of 78.2, compared to 144.3 in 2017-2019) may be due to the restrictions implemented for the COVID-19 pandemic. Nevertheless, the average weekly rate of ED admissions caused by ARI was 30.8% in 2020, as compared with 21.7% in 2017-2019. Analysis by age group showed a peak of accesses in the last weeks of 2021 for the <1 and 1-4 years old age groups. Conclusions Data on ARI-related admissions provide valuable insights into the dynamic patterns of seasonal air-borne infections and age-related vulnerabilities. This could be useful in directing health policies to identify indicators of future epidemic waves, contributing to the ongoing efforts to enhance preparedness and response strategies for respiratory infections. Key messages • It is important to create an integrated surveillance system to monitor and respond to ARIs. • Strategies should prioritise vaccination campaigns, particularly for RSV and influenza.