Introduction: Medication adherence is essential for a chronic patient in order to receive full benefits of the prescribed therapy, which would result in a better clinical outcome. Inadequate medication adherence is a significant global public health concern leading to poor health outcomes, increased morbidity and mortality as well as higher health care costs. The support for improving and maintaining patients' medication adherence is possible through various interventions. Purpose: The purpose of this thesis is to present interventions for improving medication adherence in chronic patients and their effectiveness based on the findings of existing studies. We are interested to determine the effect of interventions on medication adherence and, consequently, the impact on the outcome of the treatment. Methods: A descriptive review of scientific literature was carried out using the following databases: CINAHL, Medline, PubMed, ScienceDirect, and Cochrane Library. The search was limited to English literature published between 2007 and 2017. In addition, only randomized controlled trials measuring the effect of interventions on medication adherence and the clinical outcomes in adult chronic patients were included in the review. Results: 21 studies met the eligibility criteria and were included in the review. High blood pressure was frequently observed among many different chronic patients. Education of patients was the most frequent intervention for improving their medication adherence. Different interventions were undertaken mainly by health workers, especially by pharmacists. 10 studies have shown a statistically significant intervention effect on medication adherence in chronic patients compared to the control group and also found a statistically significant improvement regarding treatment outcomes. Among other four studies, which established no statistically significant intervention effect on medication adherence, two studies reported a statistically significant improvement in clinical outcomes compared to the control group. Discussion and conclusion: Higher representation of studies considering most frequent chronic illness of included patients is reflection of a large number of the same patients in real life and their serious health risk. Improving patients’ knowledge so they can follow the recommendations for their medication routine is absolutely necessary but not always sufficient. Due to a wide range of studies and methodological limitations, it was not possible to draw clear conclusions on the effectiveness of certain interventions for improving medication adherence in chronic patients. Nevertheless, the continuity of support that would be tailored to the patient’s needs and the collaboration between different professionals, the patient and their family seem to be very important. Further research is needed to explore the effects of medication adherence interventions among chronic patients.