Prostate cancer is the most common cancer among men in Poland. A significant proportion of prostate cancers can be cured, providing longer survival. Patients have the opportunity to undergo minimally invasive treatment methods like brachytherapy, while maintaining their previous quality of life. The disease itself, as well as treatment complications, primarily affect the functioning of the urinary and digestive systems and impact the sexual sphere. Aim: This study aims to assess the quality of life of patients after prostate brachytherapy. Methods: The research was conducted at the Lower Silesian Oncology Centre in Wroclaw. The study included fifty men aged between 51 and 85 years. The following questionnaires were used: EORTC QLQ-C30, QLQ-PR25. Scales: Katz, Mini-MAC, PSS-10. Moreover, the study used a self-designed survey covering socio-demographical factors. Results: Prostate brachytherapy has a significant impact on the degree of sexual dysfunction. Compared to sexually inactive individuals, sexually active individuals exhibit fewer negative psychological symptoms. Choosing a destructive coping strategy intensifies the occurrence of symptoms, lowers patients' level of independence, and negatively affects their quality of life. Conclusions: Brachytherapy contributes to worsening sexual function and temporarily affects urinary system function, which may lower the overall quality of life in patients.