Carob (Ceratonia siliqua L) is an evergeen plant which was once before widespread all around Croatia. Today there are fewer locations where the plant naturally grows, and even fewer organized plantations. Indigenous variety of carob is completely unexplored and little is known aout the chemical composition of the fruit and the leaves of domestic varieties. The main objective of this work was to determine the levels of flavonoids in leaves of wild trees/shrubs of carob found at 14 locations on the Dalmatian coast and islands. The level of flavonoids was determined by spectrophotometric method after consecutive extraction of the deffated leaf of carob with the organic solvents. The obtained results, expressed as equivalents of quercetin, showed that the levels of flavonoids in the leaf varies significantly depending on the locality and the gender of the plant. The concentrations of flavonoids ranged from 266.7 to 503.0 mg QUE/g in the leaves of male trees; from 297.6 to 595.4 mg QUE/g in leaves of female trees; from 405.9 to 624.5 mg QUE/g in leaves of bisexual trees. Depending on the locality we can also notice a difference: the plants of carob from the islands are richer with flavonoids than the plants which grow on the coast and inland. In addition, carob leaves collected at the site of Mali Lošinj contained significantly lower concentration of flavonoids in comparison to the south Dalmatian locations. Gender of the plant significantly affects the levels of flavonoids in the leaves: regardless of the site the level of flavonoids was the lowest in the male plants, a little higher in the leaves of the female plants and significantly higher in the leaves of the bisexual plants.