Objectives The aim of this study was to collect, systematically present and critically analyse the results of recent clinical studies on the efficacy of a standardized maritime pine bark extract available under the trade name Pycnogenol®. Material For the purpose of this specialist thesis, the literature has been searched by research topic in bibliographic and other databases (PubMed, ScienceDirect, ClinicalTrials.gov, and Google Scholar). All original scientific papers, meta-analyses, review papers and professional papers relevant to the issues of this thesis have been reviewed and analytically and critically analysed. The most important results, discussions and conclusions are summarized and presented in the thesis together with the own considerations of the studied problem. Results The paper provides a systematic review of the available clinical evidence on the effectiveness of the standardized maritime pine bark extract in the prevention and treatment of various health issues. Studied clinical trials were categorized into tables to provide insight into its effect on individual organ systems and/or diseases. It has been found that Pycnogenol shows numerous clinical effects and the most extensively studied use is for cardiovascular disorders. The majority of controlled studies are in favour of improving endothelial function and chronic venous insufficiency of subjects, demonstrating improved blood flow, normalization of blood pressure and platelet function, and reduction of venous insufficiency. Although a number of studies support VI the benefit of use in hypertension and hyperlipidemia, the results are not completely consistent. A small number of well-designed studies suggest efficacy and application in the treatment of asthma, ADHD, diabetes and its complications, gynecological problems (dysmenorrhea, menopause, and endometriosis), osteoarthritis, and cognitions. The beneficial effects of Pycnogenol have been demonstrated in a number of other indications, such as erectile dysfunction, diabetic microangiopathy, metabolic syndrome, colds, allergic rhinitis, muscle cramps and pain, etc., but those are based on few studies and/or a small number of subjects and/or methodologically poor studies. Conclusion Based on the overview of the recent clinical findings it can be concluded that supplementation with Pycnogenol has shown a number of beneficial effects on different parts of human body in health and disease. Taking into consideration the parameters monitored during the studies, it is obvious that the clinical benefit can be attributed to the antioxidant and anti-inflammatory activities of the standardized extract. Most studies and scientific evidence support the effectiveness of maritime pine bark in various cardiovascular disorders, primarily chronic venous insufficiency and venous system diseases, but also hypertension and hyperlipidemia. The positive impact of supplementation has been demonstrated in a number of disorders of the respiratory, reproductive and neurological systems, and in some inflammatory diseases and diabetes, but new, well-designed controlled studies on a large sample of subjects are needed to further confirm the usefulness of the application and to strengthen existing evidence. Future studies should also evaluate the long-term effects of Pycnogenol supplementation and determine the optimal duration of use and dosage.