Background/Objectives: Patients receiving solid organ transplantation require lifelong immunosuppression, making them more susceptible to COVID-19. Vaccination against COVID-19 is recommended for HTR. The aim of the present study was to compare the course of the disease in vaccinated and unvaccinated HTR hospitalized in a tertiary hospital in Slovenia and to evaluate possible hesitant groups. Methods: All SARS-CoV-2 positive HTR (N=79) between 1 March 2020 and 31 December 2023 at the Infectious Diseases Department, University Medical Centre Ljubljana, Slovenia, were included retrospectively. Demographic, clinical and vaccination data were extracted from medical documentation and statistical evaluation was performed. Results: The vaccination rate in the cohort was 63.3%. We found no statistically significant difference in vaccination rates regarding gender (male 68.4% vs. female 50%, p=0.128), but there was a statistically significant higher revaccination rate in males (male 52.7% vs. female 18.2%, p=0.021). Vaccinated HRT were statistically significantly older than unvaccinated (p=0.000) and had a significantly higher Charlson Comorbidity index (p=0.001). The vaccination rate among patients who received transplants before the pandemic (prior to 2020) was statistically significantly higher (71.7% vs. 46.2%; p=0.027). Conclusions: Our results indicate no significant differences in the clinical course of COVID-19 between vaccinated and unvaccinated HRT regarding acute respiratory insufficiency (ARI), length of hospital stay (LOS), intensive care unit admission and mortality. However, our findings do suggest statistically significant differences in COVID-19 vaccine acceptance rates; younger HRT and those transplanted after the pandemic are more hesitant to vaccination and female HRT accept booster doses less frequently.