The beneficial effects of olive leaves are known from ancient times. In this regard, both the olive leaves and the different preparations obtained from them (e.g. infusions, extracts) have been traditionally used for the treatment of various diseases or to alleviate the symptoms associated with different pathologies. In addition, the use of olive leaves extracts as nutraceuticals along today's continuous usage in cosmetics and medicine is common. Most of the health-related benefits of olive leaves have been associated to their high content in antioxidant bioactive compounds such as polyphenols, carotenoids, etc., being oleuropein and hydroxytyrosol some of the phenolic compounds which have attracted more interest by the both the scientific community and industry (food, pharmaceutical, among others). In this regard, olive leaves can be used to prevent oxidation processes as well as for other several applications in food industry such as to enhance the nutritive value of foods by delivering important nutrients to consumer's diets. At this stage of development, the implications of the extracts obtained from olive leaves and/or the isolated compounds on gut microbiota is scarce and limited. In the present review, the main extraction techniques (conventional and innovative), the bioaccessibility and bioavailability of the compounds found in olives as well as their impact on gut microbiota will be discussed. •Olive leaves (OL) used in the human diet as an extract, a herbal tea and a powder.•OL rich source of antioxidant bioactive compounds (eg. oleuropein, hydroxytyrosol).•There is a need to optimize extraction processes according to targeted compound.•Different biological activity according to the targeted polyphenols.•OL important role preventing oxidative stress and risk of developing chronic diseases.