Strawberries (Fragaria × ananassa Duch.), the most popular berries grown and consumed all over the world, have a unique composition of bioactive compounds, including polyphenols that determine the quality, nutritional value and sensorial properties of those fruits. The study has provided data suggesting that there are links between the presence of bioactive compounds in strawberry leaves and the presence of those compounds in strawberry fruit. Newly released and standard June-bearing strawberry cultivars (Fragaria × ananassa Duch.) were analysed with the aim of evaluating the content of health-related compounds in the fruit and leaves. The cultivars ‘Clery’ and the newly released ‘Joly’ are promising due to high levels of bioactive compounds in their fruit. The antioxidant capacity (TEAC) of the leaves was about 15 times higher than the TEAC of the fruit. Total phenolic compounds (TPC) were an important factor influencing the TEAC values of the fruit (r = 0.86). No significant correlation was found between TPC and TEAC in the leaves. The highest levels of bioactive compounds (TPC) were observed in the cultivars ‘Selvik’, ‘Diana’ and ‘Clery’. In all of the analysed cultivars a high content of agrimoniin in the leaves was correlated with low TPC and TEAC values in the fruit. Additionally, the content of free ellagic acid in the leaves showed a good correlation with the cinnamic acid derivative and ferulic acid hexose derivative in the fruit. The measurement of the content of agrimoniin and free ellagic acid in strawberry leaves could help breeders to identify cultivars with a high antioxidant capacity and a high content of TPC, cinnamic acid derivatives and ferulic acid hexose derivatives in the fruit without waiting until fructification. The paper discusses this innovative conceptual approach to increasing breeding efficiency.