Aim: Since the first cases in February 2020 till end of March 2023, 1 270 513 cases of COVID- 19 have been reported in Croatia, including 18 044 deaths. During the pandemic period with circulation of alfa and delta SARS-CoV-2 variant, many patients were admitted to hospitals in critical conditions, seemingly due to late referral to hospital. The objective was to analyze the characteristics of COVID-19 patients presented with severe acute respiratory infections (SARI) according to the length of period from the symptom onset to hospital admission and to identify possible adverse impact of the delay in hospital admission on the outcome. Materials and methods: A prospective cohort study was conducted using data from the sentinel SARI surveillance funded by the European Centre for Disease Prevention and Control. The study participants were patients meeting protocol SARI case definition, hospitalized from 1st February till 3rd October 2021 in the University Hospital Split, Split-Dalmatia County, and the General Hospital Zabok, Krapina-Zagorje County. COVID-19 was confirmed using real-time reverse transcriptase polymerase chain reaction. Data on age, gender, vaccination status, comorbidities, clinical presentation, treatment and outcome were collected using a standardized questionnaire. Descriptive and univariate analysis was conducted using MS Excel and STATA 16.1. Results and conclusion: During the observed period, 1447 COVID-19 positive SARI patients were hospitalized 0 to 43 days after the symptom onset, with 653 (45.1%) patients admitted within seven days and 794 (54.9%) thereafter. Age average was 67, ranging from 0 to 97 years old, with 844 (59%) male and 587 (41%) female patients. According to the preliminary results, patients admitted to the hospital at least seven days after the symptom onset had lower chances of fatal outcome (p