Introduction: Adherence to treatment recommendations for chronically ill patients is still a complex problem, especially among the older population. Chronic diseases, including hypertension, negatively affect patients’ quality of life (QOL). A satisfactory level of the patients’ QOL and good adherence to medication regimens can prevent complications and deterioration of daily functioning. Objectives: This cross-sectional study aimed to analyse selected sociodemographic and clinical factors affecting adherence to antihypertensive treatment in elderly patients. Material and methods: A total of 100 patients (61 females, 39 males) with hypertension who were treated in a university hospital participated in the study. Medical records were analysed to include required sociodemographic and clinical factors. Data were collected from standardized instruments: World Health Organization Quality of Life-Age (WHOQOL-AGE), the Geriatric Depression Scale (GDS), and the Adherence in Chronic Diseases Scale (ACDS). Results: The median duration of illness was 10 years (Q1 = 4.75, Q3 = 14.0). The median total QOL score was 61.06 points (Q1 = 50, Q3 = 69.23). Symptoms of depressive disorder were found in 32% of patients. There was a high level of adherence in 63% of respondents, 34% presented a moderate level, and 3% of patients adhered to a low level. Significant differences (p < 0.05) were found in the adherence levels in groups varying in depressive symptoms (rs = –0.289) and QOL results (rs = 0.33). Adherence was also significantly higher in patients with a college/university education and a good financial situation (p < 0.05). Conclusions: Education and financial standing affect adherence to antihypertensive treatment in elderly patients and should be considered in everyday clinical practice. Also, the level of QOL and depressive symptoms are significant.