Background: Bleeding following tonsillectomy is considered one of the most severe complications. Primary bleeding occurs within 24 hours of the procedure. Secondary bleeding emerges 2 to 10 days after the surgical procedure. Aim: The aim of this research is to compare the frequency of bleeding by age, gender, and clinical indication after tonsillectomy at the Department for Ear, Nose, and Throat Diseases of the Clinical Hospital Dubrava. Methods: This research was conducted as a retrospective study spanning a five-year period from 1 January 2018 to 31 December 2022. The objective was to assess the frequency and characteristics of bleeding following the surgical procedure of tonsillectomy. Data for this study were sourced from the Hospital Information System. These electronic medical records provided comprehensive details on every patient undergoing tonsillectomy during the specified period. For each patient, the following data were gathered: age, gender, clinical indication. Moreover, for patients who experienced post-operative bleeding, the subsequent information was analysed: time of onset of bleeding after the operation and the method by which the bleeding was halted (e.g. conservative treatment, surgical intervention). Results: In the period from 2018 to 2022, 1,016 patients who underwent tonsillectomy were analysed. The majority of patients (93.7%) did not experience post-operative bleeding, whereas 6.3% of patients did bleed. Among patients with bleeding, the most common diagnosis was J35.0. Males constituted 59.4% of patients with bleeding, and females 40.6%; however, the difference in bleeding occurrence between genders was not statistically significant. Statistically, there was a significant age difference between patients with various diagnoses and the method of bleeding treatment, with younger patients more frequently treated conservatively. There was no significant correlation between patient age and the time bleeding emerged. 42 out of 64 patients (65.6%) who experienced bleeding were older than 19 years, whilst merely 22 out of 64 patients (34.4%) were younger than 18 years. Conclusion: In the analysis of demographic information, although men more commonly experienced bleeding, this difference did not prove statistically significant. Amongst patients who experienced bleeding, the majority were over 19 years old, while a smaller portion was under 18 years. Additionally, the diagnosis J35.0 Chronic tonsillitis was the most frequent amongst patients with post-operative bleeding.