Polycystic ovarian syndrome (PCOS) is a heterogeneous endocrine disorder characterised by elevated levels of male hormones, acne and hirsutism. Hormonal imbalances in PCOS women can lead to immature eggs, anovulation and infertility. Plant extracts have been shown to improve PCOS however, there was a lack of systematic review on this topic. The aim of this paper was to review the plant extracts claimed to improve PCOS in the literature. In depth searches of the literature was carried out based on the Preferred Reporting Items for Systematic Review and Me- ta-analyses (PRISMA) guideline. A bibliographic search was performed on MEDLINE, Science Direct, Web of Science and Cochrane library databases using the following search terms; [‘Polycystic Ovarian Syndrome’ or ‘PCOS’] and [‘plant extracts’]. A total of 38 studies were included in the final review. 15 plant extracts hypothesised to reduce PCOS were identified; Chinese herbal medicine (n=22), Black Cohosh (n=2), Jatamansi (n=1), Tribulus (n=1), Kacip Fatimah (n=1), Fenugreek seed (n=2), Coconut tree flower (n=1), Maitake mushroom (n=1), Wood Betony (n=1), Cinnamon (n=2), Marjoran (n=1), Korean Red Ginseng (n=1), Hazelnut (n=1), Adlay (n=1) and Northern White Ce- dar (n=1). Three different models were used; randomised control trials (n=23), animal models (n=14) and non-ran- domised surveillance study (n=1). PCOS characteristics were improved with the used of plant extracts by improving insulin resistance, pregnancy outcomes and ovarian morphology. However, most of these researches are at the early stages. Further researches are needed to elucidate the mechanisms of these plant extracts in treating PCOS.