Functional foods are considered beneficial to human health due to their high nutritional values. Nowadays, there is a development in research to identify natural functional food sources high in bioactive compounds, such as antioxidants and polyphenols, as they are shown to contribute towards decreasing oxidative stress and maintaining wellbeing in human health. The objective of the present study was to determine the total antioxidant capacity and total phenolic content of Mediterranean medicinal natural herbs and wild greens aiming to create a database of medicinal plants for future potential use as functional food ingredients. A total of seventeen selected herbs and wild greens from Lemnos Island (Greece) were purchased between June and July of 2021. Extracts were prepared with an ultrasound water bath at 70^oC for 60min. The antioxidant capacity was measured with ferric reducing antioxidant power (FRAP) assay and the total polyphenolic content was determined with the Folin-Ciocalteau reagent method. The mean phenolic values ranged from 0.18 to 2282.80 mg of gallic acid / g of sample; whereas Hypericum perfoliatum L. and Hypericum perforatum L., Salvia spp., and Sideritis sp. displayed the highest contents, with a value greater than 12.20mg of gallic acid / g (p<0.05). Melissa officinalis L., Mentha Spicata, and Thymbra capitata L. obtained the highest total antioxidant capacity with an average range of 0.06 to 30.58 mmol of Fe²⁺/ L of extract (p<0.05). Pistacia lentiscus var. chia, Crataegus azarolus L., and Pancratium maritimum obtained the lowest contents from both methods. Studies have shown that medicinal plants with total antioxidant values higher than 0.87mmol/L could be applicable in the fortification of food products (i.e. yogurt). Therefore, this study suggests that most of the above medicinal plants could be a potential source of antioxidants for functional food applications while their use can enhance Mediterranean diet principles.