The aim of this study was to gain insight into the most common infections due to which patients come to the emergency unit of a hospital. Based on the obtained data from the doctors and a short interview with patients, it was assessed whether emergency antibacterial therapy is prescribed according to current national and international guidelines for the treatment of a specific infectious condition. From the data on the medical condition and other therapy used by the patients, it was assessed whether there is a risk of interactions of the prescribed emergency therapy with the chronic therapy of the patients. This observational study was conducted in one pharmacy, on 57 patients who were required to start antibacterial therapy upon discharge from the emergency department of University Hospital Centre Zagreb at the time of inclusion in the study. The obtained data were processed by methods of descriptive statistics. The study involved 30 women and 27 men. The most common indications for the use of antibacterial therapy were diseases of the genitourinary system (28 %), diseases of the respiratory system (19 %), skin and subcutaneous tissue diseases (16 %), then ICD group R - symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (14 %), eye and adnexal diseases (12 %), ICD group S - injuries, poisoning and certain other consequences with an external cause (9 %) and diseases of the vascular system and diseases of the musculoskeletal system and connective tissue. Most of the prescribed antibacterial therapy complies with some of the existing guidelines in the world, since Croatia does not have its own national guidelines for many indications. No significant interactions were found between prescribed acute antibacterial therapy and other medications used by patients. This is partly because they are mostly younger, working people, with an average age of 42.1 years. Caution should be exercised when prescribing antibiotics that are known to interact frequently and easily, such as ciprofloxacin. The analysis found that emergency department physicians often did not determine the duration of antibacterial treatment (22.8 % of total treated cases). This research showed the need for regularly updated guidelines for the treatment of the most common bacterial infections, and identified some shortcomings in prescribing acute antibacterial therapy, which shows that greater involvement of pharmacists (hospital or public) could significantly improve treatment and contribute to more rational and safer use of antibiotics, with the aim of achieving the desired treatment outcomes.