Abstract Background Non-adherence to medication is a common and complex issue faced by individuals undergoing hemodialysis (HD). However, more knowledge is needed about modifiable factors influence on non-adherence. This study investigated the prevalence of non-adherence, medication beliefs and symptom burden and severity among patients receiving HD in Denmark. Associations between non-adherence, medications beliefs and symptom burden and severity were also explored. Method A cross-sectional questionnaire-based multisite study, including 385 participants. We involved patient research consultants in the study design process and the following instruments were included: Medication Adherence Report Scale, Beliefs about Medication Questionnaire and Dialysis Symptom Index. Logistic regression analysis was performed. Results The prevalence of non-adherence was 32% (95% CI 27–37%) using a 23-point-cut-off. Just over one third reported being concerned about medication One third also believed physicians to overprescribe medication, which was associated with 18% increased odds of non-adherence. Symptom burden and severity were high, with the most common symptoms being tiredness/ lack of energy, itching, dry mouth, trouble sleeping and difficulties concentrating. A high symptom burden and/or symptom severity score was associated with an increased odd of non-adherence. Conclusion The study found significant associations between non-adherence and, beliefs about overuse, symptom burden and symptom severity. Our results suggest health care professionals (HCP) should prioritize discussion about medication adherence with patients with focus on addressing patient-HCP relationship, and patients’ symptom experience. Future research is recommended to explore the effects of systematically using validated adherence measures in clinical practice on medication adherence, patient-HCP communication and trust. Additionally, studies are warranted to further investigate the relationship between symptom experience and adherence in this population. Trial registration NCT03897231.