Fenolni spojevi predstavljaju sekundarne biljne metabolite koji imaju vrlo važnu fiziološku i morfološku ulogu u rastu i reprodukciji biljke pružajući joj i zaštitu protiv patogena i predatora. Cilj ovoga istraživanja je dobiti pregled promjena u sastavu i sadržaju fenolnih spojeva odnosno flavonola, flavanola, hidroksicimetnih i hidroksibenzojevih kiselina prisutnih u listovima četiri različite crne sorte vinove loze. Ekstrakti su analizirani tekućinskom kromatografijom visoke djelotvornosti. Dobivenim rezultatima utvrđena je značajna varijabilnost u masenim udjelima fenolnih spojeva između sorata po pojedinim terminima uzorkovanja, kao i značajna varijabilnost u sadržaju fenolnih spojeva unutar iste sorte tijekom različitih termina uzorkovanja. Phenolic compounds represent secondary plant metabolites which play an important physiological and morphological role in plant growth and reproduction. They also provide a protection against pathogens and predators. The aim of this study is to obtain an overview of changes in the composition and phenolic compounds content, more precisely flavonols, flavanols, hydroxycimetic and hydroxybenzoic acids present in the leaves of four different grapevine varieties. The extracts were analyzed by high performance liquid chromatography. Based on the obtained results, significant variability in mass shares of phenolic compounds between varieties was determined by individual sampling terms, as well as significant variability in the content of phenolic compounds within the same variety during different sampling terms.